How Do I do This Update

I have table A with 5000+ rows and table B with 2200+ rows. They are keyed on a part number. Table A includes all part numbers, table B only those that need to be updated. I've tried using an update with an embedded select using several combinations and approaches. They all update every row of table A instead of the rows that have a match in table B. Can someone help. Please email. Thanks. Received on Mon Jun 30 1997 - 00:00:00 CDT