Skip to main content

Oracle Tutorial and real time issues

Search This Blog

About Me

Get link
Facebook
X
Pinterest
Email
Other Apps

Hi,

I am Siva. I want to share my SQL knowledge to all of you through this blog.

Please write a comment if you have any doubt related to SQL Topics.

Thanks,

Siva.

Get link
Facebook
X
Pinterest
Email
Other Apps

Comments

Post a Comment

Popular Posts

DQL (OR) DRL Commands in SQL

DQL Command in SQL: DQL = Data Query Language DQL command is used to retrieve or fetch the data from a table in Database. We can also call DQL commands as "DRL" (data Retrieval language) commands. -> SELECT is the DQL command. SYNTAX 1: SELECT * from tablename; SYNTAX 2: SELECT columnName1, columnName2 from tablename; SYNATX 3: SELECT * from tablename where condition; Examples : select * from employee; ( This will fetch all columns and rows from the table) select name, salary from employee; ( This will fetch only selected columns) select * from employee where name='KRISH'; ( This will fetch based on the Where condition) Below are the few test scenarios for beginners. Practice to get better. -> Select ALL ROWS and ALL COLUMNS. -> Select ALL ROWS and PARTICULAR COLUMNS. -> Select PARTICULAR COLUMNS and ALL ROWS. -> SELECT PARTICULAR ROWS and PARTICULAR COLUMNS. If you have...

Special Operators in SQL( LIKE,NULL,BETWEEN and IN)

Special Operators in SQL Special operators are used to retrieve/get the values based on the condition specified. Below are the list of special operators. 1. IN and NOT IN 2. BETWEEN and NOT BETWEEN 3. IS NULL and IS NOT NULL 4. LIKE and NOT LIKE 1. IN and NOT IN: IN operator is used to pick the values one by one from the list of values. We can also use IN operator in place of OR operator when we are trying to to fetch/retrieve multiple values from a single column. So in this case " IN " operator performance is high compared to OR operator. Syntax : select * from tableName where columnName IN (list of values); Example : select * from employee where employee_id IN (1111,1112,1113); NOT IN operator is used to pick the values other than specified condition values. So we can use this to filter unwanted data. Syntax : Select * from tableName where columnName NOT IN (list of values); Example : Select * from employee where employ...

TCL Commands in SQL (commit, rollback and Savepoint commands in SQL)

TCL commands in SQL: TCL : Transaction Control Language. TCL commands are used to manage the transactions in database. These are used to manage the DML commands i.e Insert, Update, Delete. These TCL commands are acts like second level authentication. Suppose example, without commit system won't update the modified data into database. It just applicable for the particular session only. Below are the TCL commands. 1. Commit 2. Rollback 3. Savepoint 1. COMMIT: Syntax: COMMIT COMMIT command is used to save the transactions(Insert, Update and Delete) permanently into the database. So if we run any INSERT, UPDATE and DELETE command in SQL, System won't save/commit explicitly. So the changes applicable for the particular session only. So to avoid such issues, We have to run COMMIT command to save the transaction/update data permanently. 2. ROLLBACK: Synt...

Powered by Blogger