How code 2 left joins in UPDATE sql ???

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From: mscertified (rupert_at_tigerlily.com)
Date: 03/25/05 

Date: Fri, 25 Mar 2005 15:15:01 -0800

I have tried everything I can think of and get syntax errors. I need to do

UPDATE tblA LEFT JOIN tblB ON tblA.X = tblB.X LEFT JOIN tblC on tblA.Y =
tblC.Y
SET ...,
SET...,
etc. etc.