Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!apple!voder!blia!jeffb
From: jeffb@blia.BLI.COM (Jeff Beard)
Newsgroups: comp.databases
Subject: Re: Multiple selects
Message-ID: <12661@blia.BLI.COM>
Date: 9 Oct 90 15:31:22 GMT
References: <1990Oct4.072314.27476@monu6.cc.monash.edu.au> <1990Oct9.022119.23438@murphy.com>
Reply-To: jeffb@blia.UUCP (Jeff Beard)
Organization: Britton Lee
Lines: 21

>Select * from supp
>   where supp_nbr =
>
>      select supp_nbr from quote
>     	  where quote_nbr =
>			   select quote_nbr from quote_line
>				  where quote_line.stk_no = p_stk_no
>

You may try

  Select * from supp 
  where exists  select supp_nbr from quote 
		where exists select quote_nbr from quote_line
				  where quote_line.stk_no = p_stk_no

as 'where exists' allows a result SET to be greater than one tuple.

Sub-select querys get very inefficient so it would be better to
use a single WHERE EXISTS and a sub-select that is colapsed from the
above.