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SubQuery

Author

Topic

asif372
Posting Yak Master

100 Posts

Posted - 2013-04-25 : 02:57:26

Can any one explain me sub query in easy words ? i am new in sql

bandi
Master Smack Fu Yak Hacker

2242 Posts

Posted - 2013-04-25 : 03:09:17

If you want to get results based on the output of another query, then sub queries will be used.
You can use sub queries in the SELECT, FROM, WHERE.... clauses
Ex:
SELECT EMPLOYEE_ID, SALARY, FIRST_NAME || ' ' || LAST_NAME "Highest Paid Employee"
FROM EMPLOYEES
WHERE SALARY = (SELECT MAX (SALARY) FROM EMPLOYEES) -- this is the sub query for getting highest salary of employees

refer these links for further details:
https://www.simple-talk.com/sql/sql-training/subqueries-in-sql-server/
http://msdn.microsoft.com/en-IN/library/ms189575(v=sql.105).aspx
http://blog.sqlauthority.com/2010/06/06/sql-server-subquery-or-join-various-options-sql-server-engine-knows-the-best/

--
Chandu

visakh16
Very Important crosS Applying yaK Herder

52326 Posts

Posted - 2013-04-25 : 04:16:01

another type of subqueries are correlated subqueries where you pass column(s) from main query to it and retrieve related data from one or more tables based on passed column values

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