Re: Query regarding Intersect clause

Ajit Pradnyavant <ajit(dot)pradnyavant(at)gmail(dot)com> writes:
> I think result of INTERSECT ALL query may be :

> Srno Name
> 1 Aaaa
> 1 Aaaa

> Because intersect all clause returns the duplicate values.

No; per the documentation at
http://www.postgresql.org/docs/9.1/static/sql-select.html#SQL-INTERSECT

The result of INTERSECT does not contain any duplicate rows unless the
ALL option is specified. With ALL, a row that has m duplicates in the
left table and n duplicates in the right table will appear min(m,n)
times in the result set.

So a single instance of Aaaa is appropriate for your example. (This
definition is per the SQL standard btw.)

regards, tom lane