I have one worksheet that holds data that I need in another worksheet. I do
not want to copy and paste, because all of the data may not match up. Is
there a formula that will match the data from the two tables using a unique
identifier existing in both tables and only update those records?
Thanks.

Hi,

The standard way to do that is with VLOOKUP

=VLOOKUP(A1,Sheet2!A1:D1000,2,FALSE)

This formula would be entered in a blank column of Sheet1. A1 is the unique
identifier on sheet1, Sheet2!A1:D1000 would be a range in sheet2 where column
A contains the unique identifer which you want to match to. 2 indicates that
in this example you want the item in column B on the row with the match to be
returned. False means it is an exact match.

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If this helps, please click the Yes button.

Cheers,
Shane Devenshire