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Oracle SQL Tutorial 19 - ON DELETE (SET NULL and CASCADE)
 
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Welcome everyone! Something you need to consider when you are creating foreign keys is what happens if you delete the parent? As a reminder, the parent is the row that has the value you are referencing in the row that has a foreign key. Why is this something important to consider? It's important because foreign keys need to protect us from two primary things, unacceptable INSERT statements, and unacceptable DELETE statements. Let's see what happens when we try to insert incorrect data into the table with the foreign key: INSERT INTO projects VALUES (1, 'Update website homepage', 'CalebCurry') The response tells us plainly that there is no such user in the users table. So this works correctly. Deleting data on the other hand works a bit differently because the database does not know what you want to do with the child row when you delete the parent from the parent table. By default, we will get an error message that prevents the parent from being deleted, but there are some other options. How do we configure this? This is where the ON DELETE statement comes in. We add the keywords ON DELETE right after the foreign key and then we can give it the option of CASCADE or SET NULL. CASCADE means that if we delete the parent, we are also going to delete the child. In our situation what that means is that if somebody creates a project in our project table and then that persons account gets deleted, all of the projects he owns will also be deleted. CASCADE: CREATE TABLE projects( project_id NUMBER, Project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) NOT NULL, CONSTRAINT projects_pk PRIMARY KEY (project_id), CONSTRAINT projects_users_fk FOREIGN KEY (creator) REFERENCES users (username) ON DELETE CASCADE ) SET NULL will take the value in the child table and get rid of it. What you are left with is NULL. This means that we have an orphaned child. The first thought you might have is that it is a bad thing to have an orphaned child, but in databases that is not always so. In our application if we had it set to SET NULL, when a user account gets deleted the projects would remain in existence they would just lack a creator. This might be a good thing if you are concerned about the long term survival of a project, this might be the route you want to go. It ultimately depends on the application purpose. If you don't like CASCADE or SET NULL, you can leave the entire ON DELETE statement and just have Oracle throw an error when a parent is deleted. As for us, we are going to use ON DELETE CASCADE. We need to use this with extreme caution. If you are not careful, someday you will run a delete a row and that will cascade through you database deleting a bunch of stuff you didn't want to delete. Stuff happens, so make sure you back up your database every once in eternity. Now, in the last video we started with a database design that had three tables. We've only created two in this video. In the next video we are going to create the next one, which is a little special. Then we'll finish things up by adding some indexes. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me on Patreon! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://bit.ly/JoinCCNewsletter Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 12313 Caleb Curry
118. ON UPDATE SET NULL in SQL (Hindi)
 
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Views: 2500 Geeky Shows
MySQL 17 - ON DELETE and ON UPDATE
 
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Now, what happens when you have successfully created a reference, and now you try deleting the parent? This is where the ON DELETE clause come in. This is essentially how we configure how strict a foreign key is. There are 3 options you can give for an ON DELETE: RESTRICT / NO ACTION Yes - In MySQL they are the same, but not all DBMS. CASCADE Yes SET NULL Yes Now the default is RESTRICT. This means that when you try to delete a parent row, MySQL is going to throw an error and not let you. Cascade means that if you delete the parent row, any rows that reference that parent will also be deleted. This is pretty dangerous and not often recommended. SET NULL will set the foreign key to be NULL. Now obviously, this is going to require that the foreign key is not labelled NOT NULL. In addition to the ON DELETE clause, there is the ON UPDATE clause. This one is a little less common because it configures what happens when a parent value changes. Obviously, when you are referencing a primary key, the ON UPDATE clause is nearly useless. That's because the primary key value is never supposed to change. If, on the other hand, we have a foreign key referencing a UNIQUE column that is not a primary key, it may change occasionally. So the only times you have to worry about the ON UPDATE clause is with foreign keys referencing UNIQUE columns that are not a primary key, and when you have natural keys that break the rules and actually do change at some point in time. The ON UPDATE clause has the same options as the ON DELETE clause and they all work the same way. Now, the last thing you need to know about foreign keys is that they must match the data type of the column you are referencing. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://bit.ly/JoinCCNewsletter Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 11897 Caleb Curry
SQL Null or Empty   How to Check for Null or Empty Column in SQL Server   SQL Training Online
 
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http://www.sqltrainingonline.com SQL Null or Empty - How to Check for Null or Empty Column in SQL Server - SQL Training Online You can download the sample table script at http://www.sqltrainingonline.com/how-to-filter-for-sql-null-or-empty-string/. In this video, I show you how to filter for a SQL null or empty string. It can be difficult to filter a null because you can't simply compare with an equal sign. You have to use a special IS NULL clause to make the filter work. I also show you how to combine both the SQL Null and Empty String together in a special trick with the isnull SQL Server function. I use SQL Server 2012 to demonstrate the technique. Let me know what you think by commenting or sharing on twitter, facebook, google+, etc. If you enjoy the video, please give it a like, comment, or subscribe to my channel. You can visit me at any of the following: SQL Training Online: http://www.sqltrainingonline.com Twitter: http://www.twitter.com/sql_by_joey Google+: https://plus.google.com/#100925239624117719658/posts LinkedIn: http://www.linkedin.com/in/joeyblue Facebook: http://www.facebook.com/sqltrainingonline
Views: 15069 Joey Blue
ON DELETE CLAUSE OF FOREIGN KEY CONSTRAINT IN ORACLE SQL WITH EXAMPLE (CASCADE/SET NULL/NO ACTION)
 
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This is a free video tutorial explaining about the nonmandatory on delete clause in the foreign key constraint in Oracle SQL database, the video explains about how the on delete set null and on delete cascade works, how it can be implemented with easy to understand examples. We have also shown practical demonstration on creating the foreign key constraint, and then deleting the data from the parent table and observing the changes that take place in the child table.
Views: 1219 Kishan Mashru
Merge Statement in Oracle SQL with Example (UPDATE/DELETE or INSERT)
 
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This video demonstrates how to write a Merge Statement in oracle sql, how it is useful in doing a conditional update or delete or both of them when the condition between the target table and source table is evaluated to true, and how we can insert the record into the target table when condition is evaluated to false. The video also shows the use of UPDATE, DELETE and INSERT with Merge, and also the various possible ways to use a Merge statement!!!
Views: 7124 Kishan Mashru
114. ON DELETE SET NULL in SQL (Hindi)
 
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Please Subscribe Channel Like, Share and Comment Visit : www.geekyshows.com
Views: 3629 Geeky Shows
Oracle SQL Tutorial 18 - How to Create Foreign Keys
 
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In this video we are going to be creating foreign keys. I highly recommend watching the previous video before you watch this one. Essentially, we are creating a very simple database for a system where we can create projects and add people to those projects. We started with the users table: --Delete the table if needed: --DROP TABLE users; CREATE TABLE users( user_id NUMBER, username VARCHAR2(50 CHAR) UNIQUE, CONSTRAINT users_pk PRIMARY KEY (user_id) ); Now we are going to create a table for projects with a column that is a foreign key to the username. We're going to want to make this match data types: CREATE TABLE projects( project_id NUMBER, project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) ) Next, we need to add the column attributes we decided on last video: CREATE TABLE projects( project_id NUMBER, project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) NOT NULL ) NOT NULL because we want every project to have a creator, but we are not labeling UNIQUE because that means we could only have a specific username once in the table. We want to allow a user to create multiple projects. We also need to add a primary key: CREATE TABLE projects( project_id NUMBER, project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) NOT NULL, CONSTRAINT projects_pk PRIMARY KEY (username) ) Now, the question that remains is, how can I tell Oracle that I want the username to reference the username column of the other table? We have to make a foreign key constraint. As you've learned from the previous videos, there are about three ways to create constraints. You can do it inline at the column level, unnamed. You can do it at the column level, named, and you can do it at the Table level, named. Usually the table-level is preferred, but I will quickly remind you how to do all three again. CREATE TABLE projects( project_id NUMBER, project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) NOT NULL REFERENCES users (username), CONSTRAINT projects_pk PRIMARY KEY (project_id) ) This works, but if we want to name it, we should do this: CREATE TABLE projects( project_id NUMBER, project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) NOT NULL CONSTRAINT projects_users_fk REFERENCES users (username), CONSTRAINT projects_pk PRIMARY KEY (project_id) ) This works, but the preferred method is to do it at the table level: CREATE TABLE projects( project_id NUMBER, project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) NOT NULL, CONSTRAINT projects_pk PRIMARY KEY (project_id), CONSTRAINT projects_users_fk FOREIGN KEY (creator) REFERENCES users (username) ) Great! So you've learned how to create a foreign key, now we can see it inside of Oracle SQL Developer. One important thing when it comes to foreign keys is what happens when have data in your database and you try to delete the parent row that a row in the child table references? In the next video we are going to configure that using ON DELETE. See you all then and if you enjoy this series, please do me a huge favor by liking the video and subscribing to my YouTube channel. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ HELP ME! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://bit.ly/JoinCCNewsletter Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 17402 Caleb Curry
SQL tutorial 19: ON DELETE SET NULL clause of Foreign Key By Manish Sharma (RebellionRider)
 
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SQL Tutorial 19 : ON DELETE SET NULL foreign key Clause. Links used in the tutorial On delete set null website article [ download SQL script from same link] : http://www.rebellionrider.com/on-delete-set-null.htm Foreign Key Tutorial Video : http://youtu.be/0nbkBI5r3Gw Foreign Key Tutorial Blog : http://www.rebellionrider.com/sql-foreign-key.htm This video is the part of foreign key video In this sql tutorial you will learn the referential clause ON DELETE SET NULL of foreign key. On Delete Set null clause guarantee the relation integrity in foreign key/ Tool used in this tutorial is SQL Developer. This tutorial series is part of SQL expert exam certification training. if you are preparing for SQL certification you can use my tutorials. This SQL Tutorial is a part of free training. Copy Cloud referral link || Use this link to join copy cloud and get 20GB of free storage https://copy.com?r=j7eYO7 Contacts E-Mail [email protected] Twitter https://twitter.com/rebellionrider Instagram http://instagram.com/rebellionrider Facebook. https://www.facebook.com/imthebhardwaj Linkedin. http://in.linkedin.com/in/mannbhardwaj/ Thanks for liking, commenting, sharing and watching more of our videos This is Manish from RebellionRider.com
Views: 46631 Manish Sharma
The SQL UPDATE Statement
 
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This video tutorial covers how to update fields in a SQL database table, using the SQL UPDATE statement. More guides and tutorials: http://www.itgeared.com/.
Views: 31420 itgeared
MySQL - How to Change Null Values to 0 in SQL
 
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Get Source Code/Read : http://intactabode.com/ For Developing support email your Details at : [email protected] Install Free Trail GST Ready Accounting Package Send your Contact information Name, Email, Contact Number to email : [email protected] watch demo in English : https://www.youtube.com/watch?v=a4sFNtZuYzs&ab_channel=IntactAbode watch demo in Hindi : https://www.youtube.com/watch?v=I3eCieDpG3o&ab_channel=IntactAbode Website : http://relybill.com/ Watch More Frequently Used Sql Queries in all Databases Complete Playlist: https://www.youtube.com/playlist?list=PLErD1cRL87W992bgZ_TX7gxl5UKuP9yF9 In this videos i show how to update your null values to zero or o in sql, if you wanted change all the null values in your sql to numerical zero 0, this syntax will sure help you to solve the problem. in some cases i you wanted to display your null values to 0 in sql, mysql, oracle or any other jdbc database this querry will sure help you solve the problem in sql syntax. For Source Code Visit : http://corneey.com/wJ6X2K Subscribe to YouTube channel http://corneey.com/wJ6VoC Like us on Facebook http://corneey.com/wJ6C2l Follow us on Twitter http://corneey.com/wJ6C7x Follow me on Google+ http://corneey.com/wJ6Vhc linkedin http://corneey.com/wJ6V5g
Views: 2291 Intact Abode
SQL Server - INSERT RECORDS INTO TABLE VIA SSMS - Handling NOT NULL Fields with Default Values
 
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How to insert records into SQL Server table when NOT NULL fields have no data to insert. This tutorial explains how to make use of default values in table fields.
Views: 661 Dave Merton
SQL CASCADE, SET DEFAULT, NO ACTION
 
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Jamie King of Neumont University showing the differences between CASCADE, SET DEFAULT, NO ACTION with foreign keys.
Views: 10690 Jamie King
NULL values in DBMS...how to insert null value in table in sql
 
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how to insert null value in table in sql -~-~~-~~~-~~-~- Please watch: "हँसी नहीं रोक पाओगे 100% Guarantee | Indian Funny Videos | Whatsapp Funny Videos😀😀" https://www.youtube.com/watch?v=kbwh5NwXQYo -~-~~-~~~-~~-~- #sqltutorial#oracletutorial#databasetutorial
Views: 1264 Viral Fun Tube
Different ways to replace NULL in sql server - Part 15
 
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In this video we will learn about the different ways to replace NULL values in sql server. 1. ISNULL() function 2. CASE statement 3. COALESCE() function Text version of the video http://csharp-video-tutorials.blogspot.com/2012/08/different-ways-to-replace-null-in-sql.html Slides http://csharp-video-tutorials.blogspot.com/2013/08/part-15-different-ways-to-replace-null.html All SQL Server Text Articles http://csharp-video-tutorials.blogspot.com/p/free-sql-server-video-tutorials-for.html All SQL Server Slides http://csharp-video-tutorials.blogspot.com/p/sql-server.html All Dot Net and SQL Server Tutorials in English https://www.youtube.com/user/kudvenkat/playlists?view=1&sort=dd All Dot Net and SQL Server Tutorials in Arabic https://www.youtube.com/c/KudvenkatArabic/playlists
Views: 254176 kudvenkat
MySQL - Insert Null in Database
 
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Get Source Code/Read : http://intactabode.com/ For Developing support email your Details at : [email protected] Install Free Trail GST Ready Accounting Package Send your Contact information Name, Email, Contact Number to watch demo in English : https://www.youtube.com/watch?v=a4sFNtZuYzs&ab_channel=IntactAbode watch demo in Hindi : https://www.youtube.com/watch?v=I3eCieDpG3o&ab_channel=IntactAbode For Source Code Visit : http://corneey.com/wJ6X2K Subscribe to YouTube channel http://corneey.com/wJ6VoC Like us on Facebook http://corneey.com/wJ6C2l Follow us on Twitter http://corneey.com/wJ6C7x Follow me on Google+ http://corneey.com/wJ6Vhc linkedin http://corneey.com/wJ6V5g Watch More Frequently Used Sql Queries in all Databases Complete Playlist: https://www.youtube.com/playlist?list=PLErD1cRL87W992bgZ_TX7gxl5UKuP9yF9 how to insert null value in mysql how to update null value in sql how to insert null value in sql using c# how to insert null value in sql server 2008 sql insert null date how to insert null value in oracle how to insert null value in integer field in sql server how to insert blank value in sql
Views: 1987 Intact Abode
Learn MySQL In Arabic #18 - Constraint - Foreign Key Update, Delete
 
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Learn Foreign Key Options OnUpdate and OnDelete Cascade | Restrict | Set Null | No Action
Views: 9721 Elzero Web School
7- Oracle Database insert - update - delete - intro select - -char functions.avi
 
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7-Oracle Database - SQL - insert - update - delete - intro select - working with dates and default value - to_date and to_char functions.avi
Views: 2693 Adel Sabour
SQL with Oracle 10g XE - Using ALTER TABLE to Modify Table Columns
 
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In this video I use the ALTER TABLE command to modify an existing field column. The command will allow you to change the data types, whether the field can be null, or even the primary key. When using the ALTER TABLE command you would use the keyword MODIFY to make changes to an existing column. Be careful when changing a data type of the null field as existing data may cause an error if not in compliance with the new change. The code I used to alter the Books table is : ALTER TABLE BOOKS MODIFY ISBN_10 VARCHAR(13); This video is part of a series of videos with the purpose of learning the SQL language. For more information visit Lecture Snippets at http://lecturesnippets.com.
Views: 15198 Lecture Snippets
How to Create Foreign Key Constraint with ON DELETE SET NULL Option in SQL Server -SQL Server P81
 
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SQL Server / T-SQL Tutorial Scenario: You are working as SQL Server developer, you need to create two tables with Primary -Foreign Key Relationship. You want to create Foreign Key Constraint with setting if record will be deleted from Referenced Table (Primary Key Column Table), it should not be deleted from Parent Table ( Foreign Key Constraint Table) instead the value should be updated to Null. Link to scripts used in SQL Server / TSQL Tutorial Video http://www.techbrothersit.com/2016/04/how-to-create-foreign-key-constraint_95.html Check out our website for Different SQL Server, MSBI tutorials and interview questions such as SQL Server Reporting Services(SSRS) Tutorial SQL Server Integration Services(SSIS) Tutorial SQL Server DBA Tutorial SQL Server / TSQL Tutorial ( Beginner to Advance) http://www.techbrothersit.com/
Views: 832 TechBrothersIT
SQL,  How to insert date data type, lesson 14
 
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14th video of the series, learning structured Query Language. How to insert date data type into a column. Using oracle platform.
Views: 39975 hammadshams
SQL Tutorial - 9: Create Table Statement
 
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In this tutorial we'll learn to create tables in SQL using the CREATE TABLE Statement.
Views: 274281 The Bad Tutorials
SQL tutorials 20: On Delete Cascade Foreign Key By Manish Sharma (RebellionRider)
 
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Oracle Database 11g Tutorial 20: On delete cascade This tutorial will show you how to define foreign key with on delete cascade clause. Links Blog: http://www.rebellionrider.com/on-delete-cascade.htm SQL Tutorial 19 On delete set Null: http://www.rebellionrider.com/on-delete-cascade.htm SQL Tutorial 19 Foreign Key: http://youtu.be/0nbkBI5r3Gw Copy Cloud referral link || Use this link to join copy cloud and get 20GB of free storage https://copy.com?r=j7eYO7 Tool used in this tutorial is SQL Developer. This tutorial series is part of SQL expert exam certification training. if you are preparing for SQL certification you can use my tutorials. This SQL Tutorial is a part of free training. Contacts E-Mail [email protected] Twitter https://twitter.com/rebellionrider Instagram http://instagram.com/rebellionrider Facebook. https://www.facebook.com/imthebhardwaj Linkedin. http://in.linkedin.com/in/mannbhardwaj/ Thanks for liking, commenting, sharing and watching more of our videos This is Manish from RebellionRider.com
Views: 43423 Manish Sharma
NULL Value in sql | Part 10 | SQL tutorial for beginners | Tech Talk Tricks
 
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Welcome to our Tech Talk Tricks channel.The SQL NULL is the term used to represent a missing value. A NULL value in a table is a value in a field that appears to be blank. #TechTalkTricks #RanaSingh A field with a NULL value is a field with no value. It is very important to understand that a NULL value is different than a zero value or a field that contains spaces. Syntax The basic syntax of NULL while creating a table. SQL: CREATE TABLE CUSTOMERS( ID INT NOT NULL, NAME VARCHAR (20) NOT NULL, AGE INT NOT NULL, ADDRESS CHAR (25), SALARY DECIMAL (18, 2), PRIMARY KEY (ID) ); Here, NOT NULL signifies that column should always accept an explicit value of the given data type. There are two columns where we did not use NOT NULL, which means these columns could be NULL. A field with a NULL value is the one that has been left blank during the record creation. null value definition sql is null or empty sql is not null or empty null value statistics importance of null values in relational database sql if null sql isnull function sql if not null ************************************************** Follow Tech Talk Trick on Facebook https://www.facebook.com/techtalktricks ************************************************** Follow tech talk trick on Twitter https://twitter.com/tecktalktrick ************************************************** Follow Tech Talk Tricks on Instagram https://www.instagram.com/techtalktricks ************************************************** Subscribe tech talk tricks on YouTube https://www.youtube.com/techtalktricks ***************************************************
Views: 597 Tech Talk Tricks
mysql tutorial for beginners (7/8) : Foreign Keys (FK) & Joins
 
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mysql tutorial for beginners (7/8) : Foreign Keys (FK) & Join Foreign key relationships involve a parent table that holds the central data values, and a child table with identical values pointing back to its parent. The FOREIGN KEY clause is specified in the child table. The parent and child tables must use the same storage engine. Corresponding columns in the foreign key and the referenced key must have similar data types. The size and sign of integer types must be the same. Now, we can say: MySQL supports foreign keys, which let you cross-reference related data across tables, and foreign key constraints, which help keep this spread-out data consistent. How Foreign keys help guarantee referential integrity? For storage engines supporting foreign keys, MySQL rejects any INSERTor UPDATE operation that attempts to create a foreign key value in a child table if there is no a matching candidate key value in the parent table. When an UPDATE or DELETE operation affects a key value in the parent table that has matching rows in the child table, The result depends on the referential action specified using ON UPDATE and ON DELETE subclauses of the FOREIGN KEY clause. MySQL supports 4 options regarding the action to be taken: CASCADE: Delete or update the row from the parent table, and automatically delete or update the matching rows in the child table. SET NULL: Delete or update the row from the parent table, and set the foreign key column or columns in the child table to NULL. If you specify a SET NULL action, make sure that you have not declared the columns in the child table as NOT NULL. RESTRICT: Rejects the delete or update operation for the parent table. NO ACTION: A keyword from standard SQL. In MySQL, equivalent to RESTRICT. The MySQL Server rejects the delete or update operation for the parent table if there is a related foreign key value in the referenced table. For an ON DELETE or ON UPDATE that is not specified, the default action is always RESTRICT. FK constraint can be added using CREATE TABLE or ALTER TABLE statement First off let’s create the parent tables, I’ll begin with Tests table: CREATE TABLE Tests ( id_test INT NOT NULL AUTO_INCREMENT, title VARCHAR(25) NOT NULL, date DATE NOT NULL, PRIMARY KEY(id_test) ); And Questions table: CREATE TABLE Questions ( id_question INT NOT NULL AUTO_INCREMENT, question TEXT NOT NULL, answer TEXT NOT NULL, PRIMARY KEY(id_question) ); Now, let’s create the child table, Question_in_test: Id_test column will be FK reference to the id_test in Tests table, don’t forget both columns should be the same data types, and same size, id_question column will be FK reference to the id_question in Questions table, CREATE TABLE Question_in_test ( id_qt INT NOT NULL AUTO_INCREMENT, number TINYINT NOT NULL, value TINYINT NOT NULL, id_test INT, id_question INT, FOREIGN KEY(id_test) REFERENCES Tests(id_test) ON DELETE RESTRICT ON UPDATE CASCADE, FOREIGN KEY(id_question) REFERENCES Questions(id_question) ON DELETE NO ACTION ON UPDATE CASCADE, PRIMARY KEY(id_qt) ); The last child table is the Grade_per_question This table contains 2 FKs Id_student FK reference to the id_student in Students table, And id_question per test reference to the id question per test in Question_in_test table, ALTER TABLE grade_per_question ADD FOREIGN KEY(id_qt) REFERENCES Question_in_test(id_qt) ON DELETE NO ACTION ON UPDATE CASCADE, FOREIGN KEY(id_student) REFERENCES Students(id_student) ON DELETE RESTRICT ON UPDATE CASCADE, If you wish to specify the column on which to join two tables, use the JOIN ON construct: Students table joined with grade_per_question on id_student And grade_per_question joined with question_in_test on id_qt Question_in_test joined with tests on id_test: SELECT name,title,date,sum(grade) FROM students join grade_per_question on students.id_student = grade_per_question.id_student join question_in_test on question_in_test.id_qt = grade_per_question.id_qt join tests on tests.id_test = question_in_test.id_test Whatever kind of data you are storing in your database, it must have some value to you, therefore, it’s important that you keep backups, to protect your investment also, there will be times when you have to migrate your database over to a new server, in the next tutorial we will learn how to make backing up and restoring data in mysql. Subscribe for more: ---------------------------------------------------------------------------- https://www.youtube.com/subscription_center?add_user=saf3al2a SWE.Safaa Al-Hayali - saf3al2a
Views: 24831 Safaa Al-Hayali
SQL script to insert into many to many table
 
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Text Article http://csharp-video-tutorials.blogspot.com/2017/02/sql-script-to-insert-into-many-to-many.html Slides http://csharp-video-tutorials.blogspot.com/2017/02/sql-script-to-insert-into-many-to-many_6.html SQL Server Interview Questions and Answers text articles & slides http://csharp-video-tutorials.blogspot.com/2014/05/sql-server-interview-questions-and.html SQL Server Interview Questions and Answers playlist https://www.youtube.com/playlist?list=PL6n9fhu94yhXcztdLO7i6mdyaegC8CJwR All Dot Net and SQL Server Tutorials in English https://www.youtube.com/user/kudvenkat/playlists?view=1&sort=dd All Dot Net and SQL Server Tutorials in Arabic https://www.youtube.com/c/KudvenkatArabic/playlists In this video we will discuss how to insert data into a table that has many-to-many relationship Create table Students ( Id int primary key identity, StudentName nvarchar(50) ) Go Create table Courses ( Id int primary key identity, CourseName nvarchar(50) ) Go Create table StudentCourses ( StudentId int not null foreign key references Students(Id), CourseId int not null foreign key references Courses(Id) ) Go Students - Id column is identity column Courses - Id column is identity column StudentCourses - StudentId and CourseId columns are foreign keys referencing Id column in Students and Courses tables As you can see, StudentCourses is a bridge table that has many to many relationship with Students and Courses tables. This means a given student can be enrolled into many courses and a given course can have many students enrolled. Below is the question asked in an interview for SQL Server Developer role. Write a SQL script to insert data into StudentCourses table. Here are the rules that your script should follow. 1. There will be 2 inputs for the script Student Name - The name of the student who wants to enroll into a course Course Name - The name of the course the student wants to enroll into 2. If the student is already in the Students table, then use that existing Student Id. If the student is not already in the Students table, then a row for that student must be inserted into the Students table, and use that new student id. 3. Along the same lines, if the course is already in the Courses table, then use that existing Course Id. If the course is not already in the Courses table, then a row for that course must be inserted into the Courses table, and use that new course id. 4. There should be no duplicate student course enrollments, i.e a given student must not be enrolled in the same course twice. For example, Tom must not be enrolled in C# course twice. Answer : To avoid duplicate student course enrollments create a composite primary key on StudentId and CourseId columns in StudentCourses table. With this composite primary key in place, if someone tries to enroll the same student in the same course again we get violation of primary key constraint error. Alter table StudentCourses Add Constraint PK_StudentCourses Primary Key Clustered (CourseId, StudentId) Here is the SQL script that inserts data into the 3 tables as expected Declare @StudentName nvarchar(50) = 'Sam' Declare @CourseName nvarchar(50) = 'SQL Server' Declare @StudentId int Declare @CourseId int -- If the student already exists, use the existing student ID Select @StudentId = Id from Students where StudentName = @StudentName -- If the course already exists, use the existing course ID Select @CourseId = Id from Courses where CourseName = @CourseName -- If the student does not exist in the Students table If (@StudentId is null) Begin -- Insert the student Insert into Students values(@StudentName) -- Get the Id of the student Select @StudentId = SCOPE_IDENTITY() End -- If the course does not exist in the Courses table If (@CourseId is null) Begin -- Insert the course Insert into Courses values(@CourseName) -- Get the Id of the course Select @CourseId = SCOPE_IDENTITY() End -- Insert StudentId & CourseId in StudentCourses table Insert into StudentCourses values(@StudentId, @CourseId) If required, we can very easily convert this into a stored procedure as shown below. Create procedure spInsertIntoStudentCourses @StudentName nvarchar(50), @CourseName nvarchar(50) as Begin Declare @StudentId int Declare @CourseId int Select @StudentId = Id from Students where StudentName = @StudentName Select @CourseId = Id from Courses where CourseName = @CourseName If (@StudentId is null) Begin Insert into Students values(@StudentName) Select @StudentId = SCOPE_IDENTITY() End If (@CourseId is null) Begin Insert into Courses values(@CourseName) Select @CourseId = SCOPE_IDENTITY() End Insert into StudentCourses values(@StudentId, @CourseId) End Use the following statement to execute the stored procedure Execute spInsertIntoStudentCourses 'Tom','C#'
Views: 70320 kudvenkat
How TO DELETE ROW, MODIFY, UPDATE COLUMN, DROP TABLE in Oracle SQL Using Cmd [Hindi/Urdu].
 
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Hi Friends !!!!! In this Video we show the How to delete table, row, update etc. Oracle Databse- a) Open The Sqlplus. b) Connect The Workspace. c) Show Your Tables. Query : Select * from tab; d) Select the table where you want to delete row. Query : Delete From [Table Name] Where id=?; e) Show Your Tables. Query : Select * from tab; 1 row delete sucessfully. f) If You Modify Your Table to follow this Query : Alter table [Table Name] modify [Column Name] varchar2(10); Your table column is modified. g) If You Update row data follow this Query Update [Table Name] set [Column Name]='row data of column' where id=?; If you delete the table follow the Query : Drop Table [Table Name]; Your table is deleted sucessfully. Related video Links : How to Install Java Netbeans IDE in Windows 7, 8.1, 10 [Hindi/Urdu]: https://youtu.be/jOYMNognZXM How To Install Java On Window 10, 8.1, 7 64 bit Operating System [Hindi/Urdu] : https://youtu.be/y2-g09nY33A How to install Windows 7, 8.1,10 from a flash drive or Pandrive . [Hindi/Urdu] : https://youtu.be/s4kNcirxWrc How to Make Bootable Your Pandrive [Hindi/Urdu] : https://youtu.be/BPx_Ua_aCfY How to install Oracle 11G XE On Windows 10, 8.1, 7 Operating System in [Hindi/Urdu] : https://youtu.be/-2k4QCIpIOs How to Create Table Oracle Datbase Using Sqlplus [Hindi/Urdu] : https://youtu.be/EHnAebRP6Yw How To Insert Table Oracle Database Using Sqlplus [Hindi/Urdu]: https://youtu.be/Fu0tlCml8F8 How TO DELETE ROW, MODIFY, UPDATE COLUMN, DROP TABLE in Oracle SQL Using Cmd [Hindi/Urdu]: https://youtu.be/prz9Pr0PFEg How to recover format or delete Pandrive, Sdcard, Memory Card Or Harddisk Data [Hindi/Urdu] : https://youtu.be/0GGDHVTxDh0 How to install Oracle SQl Developer And How to Connect Your Database Sql Developer[Hindi/Urdu] : https://youtu.be/608nx3mT10c How to use SQL Distinct Keyword in Cmd Or Oracle SQL Developer [Hindi/Urdu] : https://youtu.be/ofLLZ9-EG_E How to use SQL AND Or OR operator [Hindi/Urdu] : https://youtu.be/zzqDp7U3rC8 How To Use SQL Where Operation using CMD [Hindi/Urdu] : https://youtu.be/EHmL0Wa14UY How To Use SQL ASC and DESC Operation using cmd [Hindi/Urdu] : https://youtu.be/UI0hat_RMX0 For Any Query Email Add : [email protected] Facebook Page link : https://www.facebook.com/Technical-Education-4-You-144220269545756/?ref=nf&hc_ref=ART3p2EX_iIdZHm96Uz36P99q7xfycGfo54RJafY-f0O4n1bdvWU_5xGHpPrOpLepi4
Oracle SQL Tutorial For Beginners | Oracle SQL Online Training - Session 1
 
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Course : Oracle SQL Online Training Mode of Training : Online Duration : 40 Hours Timings : Flexible Oracle SQL Online Training Demo Registration Link : http://svsoftsolutions.com/demo.aspx Introduction to SQL What is SQL? What Can SQL do? RDBMS SQL Syntax Database Tables SQL Statements Overview of Most Important SQL Commands SELECT UPDATE DELETE INSERT CREATE TABLE ALTER TABLE DROP TABLE CREATE INDEX DROP INDEX SQL SELECT Statement SELECT syntax Demo Database SELECT Column Example SELECT * Example SQL Distinct SELECT DISTINCT Statement SELECT DISTINCT Syntax SELECT DISTINCT Example SQL WHERE Clause WHERE Clause WHERE Clause Example Operators in the WHERE Clause SQL AND & OR Operators AND Operator Example OR Operator Example Combining AND & OR SQL ORDER BY ORDER BY Syntax ORDER BY Example ORDER BY DESC Example ORDER BY Several Column Examples SQL Insert Into INSERT INTO Syntax INSERT INTO Examples Insert Data into Specified Columns SQL UPDATE UPDATE Syntax UPDATE Example Watch out UPDATE statement. SQL DELETE DELETE Syntax DELETE Examples Delete All the Data SQL Aliases SQL Alias Syntax for Columns Alias Example for Table Columns Alias Example for Tables. SQL Joins Different SQL JOINs INNER JOIN LEFT OUTER JOIN RIGHT OUTER JOIN FULL OUTER JOIN SQL UNION UNION Syntax UNION Example UNION ALL Syntax UNION ALL Example SQL Insert Into Select INSERT INTO SELECT Syntax INSERT INTO SELECT Examples SQL Create Table CREATE TABLE Syntax CREATE TABLE Example SQL Constraints CREATE TABLE + CONSTRAINT Syntax NOT NULL Constraint UNIQUE Constraint UNIQUE Constraint on CREATE TABLE UNIQUE Constraint on ALTER TABLE To DROP a UNIQUE Constraint PRIMARY KEY Constraint PRIMARY KEY Constraint on CREATE TABLE PRIMARY KEY Constraint on ALTER TABLE To DROP a PRIMARY KEY Constraint FOREIGN KEY Constraint FOREIGN KEY Constraint on CREATE TABLE FOREIGN KEY Constraint on ALTER TABLE To DROP a FOREIGN KEY Constraint CHECK Constraint CHECK Constraint on CREATE TABLE CHECK Constraint on ALTER TABLE To DROP a CHECK Constraint DEFAULT Constraint on CREATE TABLE DEFAULT Constraint on ALTER TABLE To DROP a DEFAULT Constraint SQL Create Index CREATE INDEX Syntax CREATE UNIQUE INDEX Syntax CREATE INDEX Example SQL DROP Command The DROP INDEX Statement The DROP TABLE Statement The DROP DATABASE Statement The TRUNCATE TABLE Statement SQL ALTER Command The ALTER TABLE Statement ALTER TABLE Example Change Data Type Example DROP COLUMN Example SQL VIEWS CREATE VIEW Statement CREATE VIEW Syntax CREATE VIEW Examples CREATE OR REPLACE VIEW Syntax Dropping a View SQL NULL Values Working with NULL Values IS NULL IS NOT NULL SQL NULL Functions NVL COALESCE For more details visit our website : www.svsoftsolutions.com Or reach us @ USA : +1-845-915-8712 (Toll Free), India : +91-9642373173
Views: 544 SV Soft Solutions
Dynamic SQL in Stored Procedure
 
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In this video we will discuss, using dynamic sql in a stored procedure and it's implications from sql injection perspective. We will discuss performance implications of using dynamic sql in a stored procedure in a later video. Text version of the video http://csharp-video-tutorials.blogspot.com/2017/04/dynamic-sql-in-stored-procedure.html Slides http://csharp-video-tutorials.blogspot.com/2017/04/dynamic-sql-in-stored-procedure_11.html All SQL Server Text Articles http://csharp-video-tutorials.blogspot.com/p/free-sql-server-video-tutorials-for.html All SQL Server Slides http://csharp-video-tutorials.blogspot.com/p/sql-server.html All SQL Server Tutorial Videos https://www.youtube.com/playlist?list=PL08903FB7ACA1C2FB All Dot Net and SQL Server Tutorials in English https://www.youtube.com/user/kudvenkat/playlists?view=1&sort=dd All Dot Net and SQL Server Tutorials in Arabic https://www.youtube.com/c/KudvenkatArabic/playlists Consider the following stored procedure "spSearchEmployees". We implemented this procedure in Part 139 of SQL Server tutorial. This stored procedure does not have any dynamic sql in it. It is all static sql and is immune to sql injection. Create Procedure spSearchEmployees @FirstName nvarchar(100) = NULL, @LastName nvarchar(100) = NULL, @Gender nvarchar(50) = NULL, @Salary int = NULL As Begin Select * from Employees where (FirstName = @FirstName OR @FirstName IS NULL) AND (LastName = @LastName OR @LastName IS NULL) AND (Gender = @Gender OR @Gender IS NULL) AND (Salary = @Salary OR @Salary IS NULL) End Go Whether you are creating your dynamic sql queries in a client application like ASP.NET web application or in a stored procedure, you should never ever concatenate user input values. Instead you should be using parameters. Notice in the following example, we are creating dynamic sql queries by concatenating parameter values, instead of using parameterized queries. This stored procedure is prone to SQL injection. Let's prove this by creating a "Search Page" that calls this procedure. Create Procedure spSearchEmployeesBadDynamicSQL @FirstName nvarchar(100) = NULL, @LastName nvarchar(100) = NULL, @Gender nvarchar(50) = NULL, @Salary int = NULL As Begin Declare @sql nvarchar(max) Set @sql = 'Select * from Employees where 1 = 1' if(@FirstName is not null) Set @sql = @sql + ' and FirstName=''' + @FirstName + '''' if(@LastName is not null) Set @sql = @sql + ' and LastName=''' + @LastName + '''' if(@Gender is not null) Set @sql = @sql + ' and Gender=''' + @Gender + '''' if(@Salary is not null) Set @sql = @sql + ' and Salary=''' + @Salary + '''' Execute sp_executesql @sql End Go Add a Web Page to the project that we have been working with in our previous video. Name it "DynamicSQLInStoredProcedure.aspx". Copy and paste the HTML and code available on my blog at the following link http://csharp-video-tutorials.blogspot.com/2017/04/dynamic-sql-in-stored-procedure.html At this point, run the application and type the following text in the "Firsname" text and click "Search" button. Notice "SalesDB" database is dropped. Our application is prone to SQL injection as we have implemented dynamic sql in our stored procedure by concatenating strings instead of using parameters. ' Drop database SalesDB -- In the following stored procedure we have implemented dynamic sql by using parameters, so this is not prone to sql injecttion. This is an example for good dynamic sql implementation. Create Procedure spSearchEmployeesGoodDynamicSQL @FirstName nvarchar(100) = NULL, @LastName nvarchar(100) = NULL, @Gender nvarchar(50) = NULL, @Salary int = NULL As Begin Declare @sql nvarchar(max) Declare @sqlParams nvarchar(max) Set @sql = 'Select * from Employees where 1 = 1' if(@FirstName is not null) Set @sql = @sql + ' and [email protected]' if(@LastName is not null) Set @sql = @sql + ' and [email protected]' if(@Gender is not null) Set @sql = @sql + ' and [email protected]' if(@Salary is not null) Set @sql = @sql + ' and [email protected]' Execute sp_executesql @sql, N'@FN nvarchar(50), @LN nvarchar(50), @Gen nvarchar(50), @sal int', @[email protected], @[email protected], @[email protected], @[email protected] End Go On the code-behind page, use stored procedure spSearchEmployeesGoodDynamicSQL instead of spSearchEmployeesBadDynamicSQL. We do not have to change any other code. At this point run the application one more time and type the following text in the "Firstname" textbox and click the "Search" button. ' Drop database SalesDB -- Notice "SalesDB" database is not dropped, So in this case our application is not succeptible to SQL injection attack. Summary : Whether you are creating dynamic sql in a client application (like a web application) or in a stored procedure always use parameters instead of concatnating strings. Using parameters to create dynamic sql statements prevents sql injection.
Views: 26595 kudvenkat
Dynamic SQL in SQL Server
 
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Text version of the video http://csharp-video-tutorials.blogspot.com/2017/03/dynamic-sql-in-sql-server.html Slides http://csharp-video-tutorials.blogspot.com/2017/03/dynamic-sql-in-sql-server_27.html All SQL Server Text Articles http://csharp-video-tutorials.blogspot.com/p/free-sql-server-video-tutorials-for.html All SQL Server Slides http://csharp-video-tutorials.blogspot.com/p/sql-server.html All SQL Server Tutorial Videos https://www.youtube.com/playlist?list=PL08903FB7ACA1C2FB All Dot Net and SQL Server Tutorials in English https://www.youtube.com/user/kudvenkat/playlists?view=1&sort=dd All Dot Net and SQL Server Tutorials in Arabic https://www.youtube.com/c/KudvenkatArabic/playlists In this video we will discuss 1. What is Dynamic SQL 2. Simple example of using Dynamic SQL What is Dynamic SQL Dynamic SQL is a SQL built from strings at runtime. Simple example of using Dynamic SQL Here is the SQL Script to create Employees table and populate it with data Create table Employees ( ID int primary key identity, FirstName nvarchar(50), LastName nvarchar(50), Gender nvarchar(50), Salary int ) Go Insert into Employees values ('Mark', 'Hastings', 'Male', 60000) Insert into Employees values ('Steve', 'Pound', 'Male', 45000) Insert into Employees values ('Ben', 'Hoskins', 'Male', 70000) Insert into Employees values ('Philip', 'Hastings', 'Male', 45000) Insert into Employees values ('Mary', 'Lambeth', 'Female', 30000) Insert into Employees values ('Valarie', 'Vikings', 'Female', 35000) Insert into Employees values ('John', 'Stanmore', 'Male', 80000) Go One way to achieve this is by implementing a stored procedure as shown below that this page would call. Create Procedure spSearchEmployees @FirstName nvarchar(100), @LastName nvarchar(100), @Gender nvarchar(50), @Salary int As Begin Select * from Employees where (FirstName = @FirstName OR @FirstName IS NULL) AND (LastName = @LastName OR @LastName IS NULL) AND (Gender = @Gender OR @Gender IS NULL) AND (Salary = @Salary OR @Salary IS NULL) End Go The stored procedure in this case is not very complicated as we have only 4 search filters. What if there are 20 or more such filters. This stored procedure can get complex. To make things worse what if we want to specify conditions like AND, OR etc between these search filters. The stored procedure can get extremely large, complicated and difficult to maintain. One way to reduce the complexity is by using dynamic SQL as show below. Depending on for which search filters the user has provided the values on the "Search Page", we build the WHERE clause dynamically at runtime, which can reduce complexity. However, you might hear arguments that dynamic sql is bad both in-terms of security and performance. This is true if the dynamic sql is not properly implemented. From a security standpoint, it may open doors for SQL injection attack and from a performance standpoint, the cached query plans may not be reused. If properly implemented, we will not have these problems with dynamic sql. In our upcoming videos, we will discuss good and bad dynamic sql implementations. For now let's implement a simple example that makes use of dynamic sql. In the example below we are assuming the user has supplied values only for FirstName and LastName search fields. To execute the dynamicl sql we are using system stored procedure sp_executesql. sp_executesql takes two pre-defined parameters and any number of user-defined parameters. @statement - The is the first parameter which is mandatory, and contains the SQL statements to execute @params - This is the second parameter and is optional. This is used to declare parameters specified in @statement The rest of the parameters are the parameters that you declared in @params, and you pass them as you pass parameters to a stored procedure Declare @sql nvarchar(1000) Declare @params nvarchar(1000) Set @sql = 'Select * from Employees where [email protected] and [email protected]' Set @params = '@FirstName nvarchar(100), @LastName nvarchar(100)' Execute sp_executesql @sql, @params, @FirstName='Ben',@LastName='Hoskins' This is just the introduction to dynamic SQL. If a few things are unclear at the moment, don't worry. In our upcoming videos we will discuss the following 1. Implementing a real world "Search Web Page" with and without dynamic SQL 2. Performance and Security implications of dynamic sql. Along the way we will also discuss good and bad dynamic sql implementations. 3. Different options available for executing dynamic sql and their implications 4. Using dynamic sql in stored procedures and it's implications Once we discuss all the above, you will understand 1. The flexibility dynamic sql provides 2. Advantages and disadvantages of dynamic sql 3. When and when not to use dynamic sql
Views: 34057 kudvenkat
Null values in SQL Server - Part 33 Tamil
 
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Subscribe to IT PORT : https://www.youtube.com/c/itport28 SQL Server Tutorial in Tamil : https://www.youtube.com/playlist?list=PLouAaeZ4xQ64enJDwWVvN3KduuZRlUrb3 SQL Server Concepts in Tamil : https://www.youtube.com/playlist?list=PLouAaeZ4xQ67kdNIByJKAGBIBhor_h4Hs SQL Server Analytic Functions in Tamil : https://www.youtube.com/playlist?list=PLouAaeZ4xQ65XIU5azEUgLVrBKEl-jWMV SQL Server Tutorial : https://www.youtube.com/playlist?list=PLouAaeZ4xQ66AYrzPtxt2SeeR4UABcBcO SQL Server Concepts : https://www.youtube.com/playlist?list=PLouAaeZ4xQ66zRe8-nDDy-YHY2o0rmbn4 SQL Server Analytic Functions : https://www.youtube.com/playlist?list=PLouAaeZ4xQ64hTsEdhLsVBquE1vERWngX A column with a NULL value is a column with no value. If a column in a table is optional, it is possible to insert a new record or update a record without adding a value to this column. Then, the column will be saved with a NULL value. Explained in Tamil
Views: 268 IT Port
Part 2   SQL query to get organization hierarchy
 
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Link for all dot net and sql server video tutorial playlists http://www.youtube.com/user/kudvenkat/playlists Link for slides, code samples and text version of the video http://csharp-video-tutorials.blogspot.com/2014/05/part-2-sql-query-to-get-organization.html To get the best out of this video, the following concepts need to be understood first. These are already discussed in SQL Server Tutorial. 1. Self-Join - http://www.youtube.com/watch?v=qnYSN_7qwgg 2. CTE - http://www.youtube.com/watch?v=ZXB5b-7HJHk 3. Recursive CTE - http://www.youtube.com/watch?v=GGoV0wTMCg0 Here is the problem definition: 1. Employees table contains the following columns a) EmployeeId, b) EmployeeName c) ManagerId 2. If an EmployeeId is passed, the query should list down the entire organization hierarchy i.e who is the manager of the EmployeeId passed and who is managers manager and so on till full hierarchy is listed. For example, Scenario 1: If we pass David's EmployeeId to the query, then it should display the organization hierarchy starting from David. Scenario 2: If we pass Lara's EmployeeId to the query, then it should display the organization hierarchy starting from Lara. We will be Employees table for this demo. SQL to create and populate Employees table with test data Create table Employees ( EmployeeID int primary key identity, EmployeeName nvarchar(50), ManagerID int foreign key references Employees(EmployeeID) ) GO Insert into Employees values ('John', NULL) Insert into Employees values ('Mark', NULL) Insert into Employees values ('Steve', NULL) Insert into Employees values ('Tom', NULL) Insert into Employees values ('Lara', NULL) Insert into Employees values ('Simon', NULL) Insert into Employees values ('David', NULL) Insert into Employees values ('Ben', NULL) Insert into Employees values ('Stacy', NULL) Insert into Employees values ('Sam', NULL) GO Update Employees Set ManagerID = 8 Where EmployeeName IN ('Mark', 'Steve', 'Lara') Update Employees Set ManagerID = 2 Where EmployeeName IN ('Stacy', 'Simon') Update Employees Set ManagerID = 3 Where EmployeeName IN ('Tom') Update Employees Set ManagerID = 5 Where EmployeeName IN ('John', 'Sam') Update Employees Set ManagerID = 4 Where EmployeeName IN ('David') GO Here is the SQL that does the job Declare @ID int ; Set @ID = 7; WITH EmployeeCTE AS ( Select EmployeeId, EmployeeName, ManagerID From Employees Where EmployeeId = @ID UNION ALL Select Employees.EmployeeId , Employees.EmployeeName, Employees.ManagerID From Employees JOIN EmployeeCTE ON Employees.EmployeeId = EmployeeCTE.ManagerID ) Select E1.EmployeeName, ISNULL(E2.EmployeeName, 'No Boss') as ManagerName From EmployeeCTE E1 LEFT Join EmployeeCTE E2 ON E1.ManagerID = E2.EmployeeId
Views: 261545 kudvenkat
T SQL Lesson13 ON DELETE,ON UPDATE CASCADE/ NO ACTION/ SET NULL/ SET DEFAULT Bhaskar Reddy
 
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Jamie King of Neumont University showing the differences between CASCADE, SET DEFAULT, NO ACTION with foreign keys. Komplette Liste der Videos und zusätzliches Material auf Informatik, Uni Saarland: Bachelor: . Now, what happens when you have successfully created a reference, and now you try deleting the parent? This is where the ON DELETE clause comes in.
Views: 47 Trenton Kim
Oracle SQL Tutorial For Beginners | Oracle SQL Online Training - Session 2
 
01:03:12
Course : Oracle SQL Online Training Mode of Training : Online Duration : 40 Hours Timings : Flexible Oracle SQL Online Training Demo Registration Link : http://svsoftsolutions.com/demo.aspx Introduction to SQL What is SQL? What Can SQL do? RDBMS SQL Syntax Database Tables SQL Statements Overview of Most Important SQL Commands SELECT UPDATE DELETE INSERT CREATE TABLE ALTER TABLE DROP TABLE CREATE INDEX DROP INDEX SQL SELECT Statement SELECT syntax Demo Database SELECT Column Example SELECT * Example SQL Distinct SELECT DISTINCT Statement SELECT DISTINCT Syntax SELECT DISTINCT Example SQL WHERE Clause WHERE Clause WHERE Clause Example Operators in the WHERE Clause SQL AND & OR Operators AND Operator Example OR Operator Example Combining AND & OR SQL ORDER BY ORDER BY Syntax ORDER BY Example ORDER BY DESC Example ORDER BY Several Column Examples SQL Insert Into INSERT INTO Syntax INSERT INTO Examples Insert Data into Specified Columns SQL UPDATE UPDATE Syntax UPDATE Example Watch out UPDATE statement. SQL DELETE DELETE Syntax DELETE Examples Delete All the Data SQL Aliases SQL Alias Syntax for Columns Alias Example for Table Columns Alias Example for Tables. SQL Joins Different SQL JOINs INNER JOIN LEFT OUTER JOIN RIGHT OUTER JOIN FULL OUTER JOIN SQL UNION UNION Syntax UNION Example UNION ALL Syntax UNION ALL Example SQL Insert Into Select INSERT INTO SELECT Syntax INSERT INTO SELECT Examples SQL Create Table CREATE TABLE Syntax CREATE TABLE Example SQL Constraints CREATE TABLE + CONSTRAINT Syntax NOT NULL Constraint UNIQUE Constraint UNIQUE Constraint on CREATE TABLE UNIQUE Constraint on ALTER TABLE To DROP a UNIQUE Constraint PRIMARY KEY Constraint PRIMARY KEY Constraint on CREATE TABLE PRIMARY KEY Constraint on ALTER TABLE To DROP a PRIMARY KEY Constraint FOREIGN KEY Constraint FOREIGN KEY Constraint on CREATE TABLE FOREIGN KEY Constraint on ALTER TABLE To DROP a FOREIGN KEY Constraint CHECK Constraint CHECK Constraint on CREATE TABLE CHECK Constraint on ALTER TABLE To DROP a CHECK Constraint DEFAULT Constraint on CREATE TABLE DEFAULT Constraint on ALTER TABLE To DROP a DEFAULT Constraint SQL Create Index CREATE INDEX Syntax CREATE UNIQUE INDEX Syntax CREATE INDEX Example SQL DROP Command The DROP INDEX Statement The DROP TABLE Statement The DROP DATABASE Statement The TRUNCATE TABLE Statement SQL ALTER Command The ALTER TABLE Statement ALTER TABLE Example Change Data Type Example DROP COLUMN Example SQL VIEWS CREATE VIEW Statement CREATE VIEW Syntax CREATE VIEW Examples CREATE OR REPLACE VIEW Syntax Dropping a View SQL NULL Values Working with NULL Values IS NULL IS NOT NULL SQL NULL Functions NVL COALESCE For more details visit our website : www.svsoftsolutions.com Or reach us @ USA : +1-845-915-8712 (Toll Free), India : +91-9642373173
Views: 46 SV Soft Solutions
Alter database table columns without dropping table   Part 67
 
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In this video, we will discuss, altering a database table column without having the need to drop the table. Let's understand this with an example. Text version of the video http://csharp-video-tutorials.blogspot.com/2013/08/part-67-alter-database-table-columns.html Slides http://csharp-video-tutorials.blogspot.com/2013/09/part-67-alter-database-table-columns.html All SQL Server Text Articles http://csharp-video-tutorials.blogspot.com/p/free-sql-server-video-tutorials-for.html All SQL Server Slides http://csharp-video-tutorials.blogspot.com/p/sql-server.html All Dot Net and SQL Server Tutorials in English https://www.youtube.com/user/kudvenkat/playlists?view=1&sort=dd All Dot Net and SQL Server Tutorials in Arabic https://www.youtube.com/c/KudvenkatArabic/playlists We will be using table tblEmployee for this demo. Use the sql script below, to create and populate this table with some sample data. Create table tblEmployee ( ID int primary key identity, Name nvarchar(50), Gender nvarchar(50), Salary nvarchar(50) ) Insert into tblEmployee values('Sara Nani','Female','4500') Insert into tblEmployee values('James Histo','Male','5300') Insert into tblEmployee values('Mary Jane','Female','6200') Insert into tblEmployee values('Paul Sensit','Male','4200') Insert into tblEmployee values('Mike Jen','Male','5500') The requirement is to group the salaries by gender. To achieve this we would write a sql query using GROUP BY as shown below. Select Gender, Sum(Salary) as Total from tblEmployee Group by Gender When you execute this query, we will get an error - Operand data type nvarchar is invalid for sum operator. This is because, when we created tblEmployee table, the "Salary" column was created using nvarchar datatype. SQL server Sum() aggregate function can only be applied on numeric columns. So, let's try to modify "Salary" column to use int datatype. Let's do it using the designer. 1. Right click on "tblEmployee" table in "Object Explorer" window, and select "Design" 2. Change the datatype from nvarchar(50) to int 3. Save the table At this point, you will get an error message - Saving changes is not permitted. The changes you have made require the following tables to be dropped and re-created. You have either made changes to a table that can't be re-created or enabled the option Prevent saving changes that require the table to be re-created. So, the obvious next question is, how to alter the database table definition without the need to drop, re-create and again populate the table with data? There are 2 options Option 1: Use a sql query to alter the column as shown below. Alter table tblEmployee Alter column Salary int Option 2: Disable "Prevent saving changes that require table re-creation" option in sql server 2008 1. Open Microsoft SQL Server Management Studio 2008 2. Click Tools, select Options 3. Expand Designers, and select "Table and Database Designers" 4. On the right hand side window, uncheck, Prevent saving changes that require table re-creation 5. Click OK
Views: 85221 kudvenkat
Update and Insert data in database from datagridview
 
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Connect with me On LinkedIn: https://www.linkedin.com/in/bhubanshrestha Sometime user needs to update large amount of data in such case updating data from datagrid view is good choice because user gets all information in a row format. In this video tutorial you will learn how to update database table from datagrid view. You can insert, upadate and delete data of database from datagrid view. In this video tutorial deleting is not shown but it is very simple. Just select row then update. NOTE You have to include primary key column in data grid view. If you want to hide primary key column to user then you can achieve this by datagridview1.Columns[0].Visible=false ;//0 is the index of primary key column OR datagridview1.Columns["PrimaryKey"].Visible=false; //PrimaryKey is a column header text of primary key.
Views: 422574 Bhuban Shrestha
Oracle SQL Tutorial 21 - How to Create / Drop Indexes
 
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In the last video, we wrote up the SQL to create three tables: CREATE TABLE users( user_id NUMBER, username VARCHAR2(50 CHAR) UNIQUE, CONSTRAINT users_pk PRIMARY KEY (user_id) ); CREATE TABLE projects( project_id NUMBER, Project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) NOT NULL, CONSTRAINT projects_pk PRIMARY KEY (project_id), CONSTRAINT projects_users_fk FOREIGN KEY (creator) REFERENCES users (username) ON DELETE CASCADE ); CREATE TABLE project_users( project_id NUMBER NOT NULL REFERENCES projects (project_id) ON DELETE CASCADE, user_id NUMBER NOT NULL REFERENCES users (user_id) ON DELETE CASCADE, CONSTRAINT project_users_pk PRIMARY KEY (project_id, user_id) ); I'm going to increase the size of the users table a bit by adding a first and last name column. CREATE TABLE users( user_id NUMBER, username VARCHAR2(50 CHAR) UNIQUE, first_name VARCHAR2(50 CHAR), last_name VARCHAR2 (50 CHAR), CONSTRAINT users_pk PRIMARY KEY (user_id) ); But before we finish this design, we should consider indexing certain columns. What columns should we index? Well, as a reminder, the columns that are indexed by default are columns with the UNIQUE constraint, and those that are labeled as primary keys. Columns that are not indexed but often should be are those labeled as a foreign key. The column that jumps out the most to me is the creator column of the project table. It's the only foreign key that is not part of some index. Let's fix this by creating our first index. The way we do that is with the CREATE INDEX command. CREATE INDEX projects_creator_ix ON projects (creator) What naming convention are we following for the index? We are naming it by the table name, followed by an underscore, followed by the column, followed by an underscore, followed by an ix (for index). In this situation it does not apply, but if our foreign key column is labeled as UNIQUE, we can add the UNIQUE keyword like this: CREATE UNIQUE INDEX projects_creator_ix ON projects (creator) Now if you want to get rid of an INDEX, you can use this command: DROP INDEX projects_creator_ix Now, if we want to select data from the user table and the project table we can do that much faster. That's because the foreign key and column it references are both indexed and those are the columns we would do the join on. We will discuss how to do joins in a future video. So what are some potential problems with this database design? Overall, it is pretty good. With this design though we need to make sure there is no way for someone to update a user's username. In the next video we are going to discuss why. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me on Patreon! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://bit.ly/JoinCCNewsletter Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 7192 Caleb Curry
ADD ROW by using INSERT INTO and having one NULL value,
 
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I am inserting a new row with my information and giving my cell phone number as a null value. Afterwards I use the DELETE statement to remove the row I added
Views: 995 Roger Perez
How to create Foreign Key Constraint With ON UPDATE CASCADE in SQL Server - SQL Server  Tutorial 79
 
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SQL Server / T-SQL Tutorial Scenario: In previous posts, we learn that if we have Foreign key Constraint with default setting and we try to update the value in column in Reference Table which is used as Reference Column in Foreign Key Constraint, we get error. We discussed multiple ways to handle the situation, please check this link. Foreign Key Constraint does provide the option to set the Cascading action, we can create Foreign Key Constraint with Cascading Update. If Update Cascading settings is used, when we update the value in Referenced Table , it will also update the value in parent table (Foreign Key Table) column. Link to scripts used in SQL Server / TSQL Tutorial Video http://www.techbrothersit.com/2016/04/how-to-create-foreign-key-constraint.html Check out our website for Different SQL Server, MSBI tutorials and interview questions such as SQL Server Reporting Services(SSRS) Tutorial SQL Server Integration Services(SSIS) Tutorial SQL Server DBA Tutorial SQL Server / TSQL Tutorial ( Beginner to Advance) http://www.techbrothersit.com/
Views: 2680 TechBrothersIT
SQL tutorials 17: SQL Primary Key constraint,  Drop primary Key
 
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Blog link: http://www.rebellionrider.com/sql-primary-key.htm SQL tutorial on Primary key / SQL Primary key, In this tutorial you will learn about simple primary key, composute primary key, how to drop primary key. defining primary key using create table and alter table along with many other things. Tool used in this tutorial is SQL Developer. This tutorial series is part of SQL expert exam certification training. if you are preparing for SQL certification you can use my tutorials. This SQL Tutorial is a part of free training. Copy Cloud referral link || Use this link to join copy cloud and get 20GB of free storage https://copy.com?r=j7eYO7 Contacts E-Mail [email protected] Twitter https://twitter.com/rebellionrider Instagram http://instagram.com/rebellionrider Facebook. https://www.facebook.com/imthebhardwaj Linkedin. http://in.linkedin.com/in/mannbhardwaj/ Thanks for linking, commenting, sharing and watching more of our videos This is Manish from RebellionRider.com So Primary Key There are two types of Primary keys First is Simple primary Key: Primary key which Involves only one column and Second is Composite Primary Key: Primary Key which involves more than one column. We will start with Simple primary key. You can create Primary key either with Create Table statement of by using Alter table Statement. Let's define simple primary key using create table statements. With create table statement we can either define primary key at column level or at table level. We will start with defining Primary key at column level using create table statement. You just have to put keyword Primary key after data type and size of column while defining a column of a table. Here oracle server will create a primary key on product id with default constraint name which will be slightly difficult to understand. You can give your own name to your constraint which is also a good practice.
Views: 95709 Manish Sharma
7 - Checking before insert, Stop duplicate entries  - Java Swing Project
 
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In this video we are going to write code to stop duplicate entries, it happen when we insert form data in database table directly, What we need to do is that we have to insert in database table before checking with sql query. Download Source Code : https://github.com/KamaleshSah/Bus-Managment-Application
Views: 6365 KAMLESHUTUBE
Learn Oracle | How to Create a Table using SQL | Not Null, Unique Key, Primary Key
 
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Pebbles present, Learn Oracle 10g with Step By Step Video Tutorials. Learn Oracle 10g Tutorial series contains the following videos : Learn Oracle - History of Oracle Learn Oracle - What is Oracle - Why do we need Oracle Learn Oracle - What is a Database Learn Oracle - What is Grid Computing Learn Oracle - What is Normalization Learn Oracle - What is ORDBMS Learn Oracle - What is RDBMS Learn Oracle - Alias Names, Concatenation, Distinct Keyword Learn Oracle - Controlling and Managing User Access (Data Control Language) Learn Oracle - Introduction to SQL Learn Oracle - Oracle 10g New Data Types Learn Oracle - How to Alter a Table using SQL Learn Oracle - How to Create a Package in PL SQL Learn Oracle - How to Create a Report in SQL Plus Learn Oracle - How to Create a Table using SQL - Not Null, Unique Key, Primary Key Learn Oracle - How to Create a Table using SQL Learn Oracle - How to Create a Trigger in PL SQL Learn Oracle - How to Delete Data from a Table using SQL Learn Oracle - How to Drop and Truncate a Table using SQL Learn Oracle - How to Insert Data in a Table using SQL Learn Oracle - How to open ISQL Plus for the first time Learn Oracle - How to Open SQL Plus for the First Time Learn Oracle - How to Update a Table using SQL Learn Oracle - How to use Aggregate Functions in SQL Learn Oracle - How to use Functions in PL SQL Learn Oracle - How to use Group By, Having Clause in SQL Learn Oracle - How to Use Joins, Cross Join, Cartesian Product in SQL Learn Oracle - How to use Outer Joins (Left, Right, Full) in SQL Learn Oracle - How to use the Character Functions, Date Functions in SQL Learn Oracle - How to use the Merge Statement in SQL Learn Oracle - How to use the ORDER BY Clause with the Select Statement Learn Oracle - How to use the SELECT Statement Learn Oracle - How to use the Transactional Control Statements in SQL Learn Oracle - How to use PL SQL Learn Oracle - Data Types in PL SQL Learn Oracle - Exception Handling in PL SQL Learn Oracle - PL SQL Conditional Logics Learn Oracle - PL SQL Cursor Types - Explicit Cursor, Implicit Cursor Learn Oracle - PL SQL Loops Learn Oracle - Procedure Creation in PL SQL Learn Oracle - Select Statement with WHERE Cause Learn Oracle - SQL Operators and their Precedence Learn Oracle - Using Case Function, Decode Function in SQL Learn Oracle - Using Logical Operators in the WHERE Clause of the Select Statement Learn Oracle - Using Rollup Function, Cube Function Learn Oracle - Using Set Operators in SQL Learn Oracle - What are the Different SQL Data Types Learn Oracle - What are the different types of Databases Visit Pebbles Official Website - http://www.pebbles.in Subscribe to our Channel – https://www.youtube.com/channel/UCNNjWVsQqaMYccY044vtHJw?sub_confirmation=1 Engage with us on Facebook at https://www.facebook.com/PebblesChennai Please Like, Share, Comment & Subscribe
Views: 177 Pebbles Tutorials
Insert and Commit: Databases for Developers #7
 
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You load data into your database tables with an insert statement. In this episode Chris discusses how to use single and multirow inserts and their pros and cons. He also covers how to persist your changes to the database with commit. See the full syntax for insert in the SQL reference guide: http://docs.oracle.com/database/122/SQLRF/INSERT.htm#SQLRF01604 Take the Databases for Developers FREE SQL course at https://devgym.oracle.com/devgym/database-for-developers.html Need help with SQL? Ask us over on AskTOM: https://asktom.oracle.com Twitter: https://twitter.com/ChrisRSaxon Daily SQL Twitter tips: https://twitter.com/SQLDaily All Things SQL blog: https://blogs.oracle.com/sql/ ============================ The Magic of SQL with Chris Saxon Copyright © 2015 Oracle and/or its affiliates. Oracle is a registered trademark of Oracle and/or its affiliates. All rights reserved. Other names may be registered trademarks of their respective owners. Oracle disclaims any warranties or representations as to the accuracy or completeness of this recording, demonstration, and/or written materials (the “Materials”). The Materials are provided “as is” without any warranty of any kind, either express or implied, including without limitation warranties or merchantability, fitness for a particular purpose, and non-infringement.
Views: 4732 The Magic of SQL
SQL Server Management Studio GUI - Insert Null
 
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A quick video that shows how to insert a NULL value into a field using the SQL Server Management Studio GUI.
Views: 573 Clarative
CREATE, INSERT and SELECT commands
 
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SQL is a special-purpose programming language designed for managing data in a relational database, and is used by a huge number of apps and organizations. Watch this Video to learn basics of SQL. This Video covers below topics about SQL. What is Database What is Database Table What is Database Fields and Records What is Oracle What is RDBMS and how it is different from flat files What is SQL Is SQL common for all RDBMS packages, prove it Installing Oracle CREATE, INSERT and SELECT commands DELETE and UPDATE commands SELECT command with WHERE condition LIKE 'pattern' Operator IN Operator BETWEEN Operator Pseudo Columns Data Types in Oracle ORDER BY Clause in Oracle RENAME Table and DROP Table in Oracle Savepoint, Rollback and Commit in Oracle Create Tablespace, Create User, Create Role, Drop Role, Drop User, Drop Tablespace in Oracle Tablespace and Datafile in Oracle Alter Tablespace in Oracle Insert multiple records in one or more tables at once in Oracle Grant, Revoke and Grant Table View to other user in Oracle Referential Integrity in Oracle Column Alias in Oracle Table Alias in Oracle Equi Join and Non Equi Join in Oracle Self Join in Oracle Natural Join in Oracle Cross Join in Oracle Outer Join - (Left Outer Join, Right Outer Join and Full Outer Join) in Oracle Anti Join in Oracle Column Format in Oracle Aggregate Functions in Oracle Character Functions in Oracle Number Functions in Oracle Conversion Functions To Char, To Date, NVL, Decode in Oracle Date Functions - Add Months, Last Day, Months Between, Next Day, To Date, New Time in Oracle SQL Commands Type in Oracle SQL Buffer Commands in Oracle Ed or Edit Buffer Command in Oracle IN and NOT IN Operators in Oracle Not Null Constraint in Oracle Unique Constraint in Oracle Primary Key and Foreign Key Constraints in Oracle Check Constraint in Oracle Order By Clause in Oracle Group By Clause in Oracle Having Clause in Oracle Subquery or Inner Query or Nested Query in Oracle Union, Union All, Intersect and Minus Operators in Oracle Data Dictionaries TAB, ALL TABLES, ALL SEQUENCES, ALL VIEWS etc in Oracle What are SQL, PLSQL, TSQL and SQL Plus ALTER TABLE ADD new column and DROP existing column in Oracle ALTER TABLE to Modify existing column in Oracle ALTER TABLE to ADD and DROP integrity constraints in Oracle Create, Alter and Drop Sequence in Oracle Create, Alter and Drop named constraints in Oracle Subquery in Oracle Set Union, Union All, Intersect, Minus Operators in Oracle Execute commands written in physical file Getting started with SQL Plus Reports - Part 1 Getting started with SQL Plus Reports - Part 2 Getting started with SQL Plus Reports - Part 3 Views in Oracle Input Variables in Oracle SQL Plus Define Variables in Oracle Bind Variables in Oracle Introduction to PLSQL in Oracle IF ELSE construct in PLSQL Oracle FOR LOOP Looping Command in PLSQL Oracle LOOP Looping Command in PLSQL Oracle WHILE Looping Command in PLSQL Oracle PLSQL Table in Oracle Exception in PLSQL Oracle Tax Calculator and Exception Handling in PLSQL Oracle Introduction to Cursor in PLSQL Oracle Cursor Examples in PLSQL Oracle UPDATE and DELETE using Cursor in PLSQL Oracle Introduction to TRIGGER in PLSQL Oracle AFTER INSERT fire UPDATE Command in Trigger AFTER INSERT or UPDATE or DELETE Commands in Trigger Statement Level Trigger in PLSQL Oracle
Views: 91 Aap Koun