On Fri, 2007-05-04 at 18:22 -0400, Vitali Lovich wrote: > Hi, > > I was wondering what would be the optimal way to select 1 matching row > from multiple tables. Here is the scenario. > > Multiple tables contain a primary key KEY. If Table1 contains a > matching KEY, then I want that row from Table1. Only if it isn't in > Table1, then look in Table2 if it is there. If not in Table2 go on to > Table3, etc etc. > > Is there a way to do this using SQL, or should I just break this up into > multiple queries and have the logic in C - this is for an embedded > system, so I want to use the least amount of memory & CPU (memory is > more important though).
How about this: SELECT * FROM tbl1 WHERE key = $key UNION ALL SELECT * FROM tbl2 WHERE key = $key LIMIT 1; Although technically, using LIMIT without ORDER BY is a bad thing. > > Thanks > > ----------------------------------------------------------------------------- > To unsubscribe, send email to [EMAIL PROTECTED] > ----------------------------------------------------------------------------- > ----------------------------------------------------------------------------- To unsubscribe, send email to [EMAIL PROTECTED] -----------------------------------------------------------------------------
