Optimizer behavior - DOH!

Does the optimizer use partial indexes? In other words, if I have an index on the sku column, warehouse column and the date column, do I have to include all three of those in my where-clause? In former times I've selected using only one of the three and the Optimizer will use the index. Now, sometimes it does and sometimes I have to include all three in order to use the index. Sometimes the order matters and other times order of the columns makes no difference at all! Dopey! Does anybody have a clue as to how the optimizer makes its choices? -- Bob Payne Software Development Manager PC Service Source email: bpayne@netcom.com 2350 Valley View Dallas, TX 75234 (214) 481-4707 WWW: http://www.pcss.net/~bpayne