Using case or if to return multiple rows

Hello all,

I want to select data from two diffrent table based on third tables column
somthing like:

select case when t3.date='xxxx' then
select * from table1

else
select * from table 2

from table3 t3 where t3.date='xxxxx'

Problem is that I have to do it in Plain SQL.

Is there a anyway.

Thanks in Advance

With egards
Ashish....