"select 1 where false" does indeed indicate an empty set. I was hoping for something more elegant, but I'll take what I can get. :)
--- Bruno Wolff III <[EMAIL PROTECTED]> wrote: > On Thu, Jun 08, 2006 at 14:40:12 -0700, > CG <[EMAIL PROTECTED]> wrote: > > PostgreSQL 8.1 > > > > I've been trying to write a SQL prepare routine. One of the challenging > > elements I'm running into is an empty set ... > > > > "select foo from bar where foo in ? ;" > > > > What if "?" is an set with zero elements? What is the proper value to use > to > > replace "?" indicating an empty set? > > Something like the following suggests you can put a subquery there that > returns > 0 rows. I don't think that wil work for prepared queries though; so it may > not > help you. > > bruno=> select * from test where test in (select 1 where false); > test > ------ > (0 rows) > > __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
