Does a sub-query require an alias ?

Hello,

As the subject says, do I have to have an alias for the table in all the sub-queries that are being used ? Say I have a query

select * from table1 a
where (a.col1, a.col2) in

      (select col4, col5 
		from table2)

Field names col4 and col5 in the select statement of the subquery do not exist in table2 but exist in table1, the query works without any error message whatsoever. Is this documented somewhere ?

Venkat Raju Received on Thu Nov 11 1993 - 22:57:37 CET