On Fri, Feb 24, 2006 at 11:57:57AM +0530, sandhya wrote: > In select lo_unlink(objid) from (select distinct objid from filetbl)AS s; > the above query what is that 'S' stands for in AS 'S' "s" is a table alias, which is required for a subquery. The choice of "s" is arbitrary; it can be any valid label. http://www.postgresql.org/docs/8.1/interactive/queries-table-expressions.html#QUERIES-SUBQUERIES -- Michael Fuhr