Multiple Sub Queries - ORACLE

Sub Queries:
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1. Single Row Sub Query - Inner query retrives only one row
2. Multiple Row Sub Query - Inner query retrives many rows

select name,salary from ex_details where salary > (Select salary from ex_details where name='DAS');

Multiple Sub Queries:
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select * from emp where salary < ANY (select salary from emp where dept=200);
// just like using OR operator
select * from emp where salary < ALL (select salary from emp where dept=200);
// just like using AND operator
select * from emp where salary IN (select salary from emp where dept=200);
// comparing each member


select name, salary from ex_details where dcode=(select e.dcode from ex_country l,ex_details e
where e.name='MARTIN' and (l.loc_id=e.loc_id))