Re: SQL query...

>if i have 5 tables and all of it has column X and i wanted to get unique
>values in column X for all tables..

>can i do it in one query?

sure. this is one way to do this:
select distinct foo.X from (
  select X from table1
  union
  select X from table2
  ....
 ) as foo;

if the values are unique within every table, then you might want to omit the
surrounding select.