Published March 28, 2012 by

Complex Queries in SQL ( Oracle )

These questions are the most frequently asked in interviews.


1.To fetch ALTERNATE records from a table. (EVEN NUMBERED)

select * from emp where rowid in (select decode(mod(rownum,2),0,rowid, null) from emp);

2.To select ALTERNATE records from a table. (ODD NUMBERED)

select * from emp where rowid in (select decode(mod(rownum,2),0,null ,rowid) from emp);

3.Find the 3rd MAX salary in the emp table.

select distinct sal from emp e1 where 3 = (select count(distinct sal) from emp e2 where e1.sal <= e2.sal);

4.Find the 3rd MIN salary in the emp table.

select distinct sal from emp e1 where 3 = (select count(distinct sal) from emp e2where e1.sal >= e2.sal);

5.Select FIRST n records from a table.

select * from emp where rownum <= &n;

6.Select LAST n records from a table
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