If you are using a sub-query then the parenthesis are needed. Just omit the single quotes.
$sth=$dbh->prepare("Update Customers set RESULTS = (?) where rec_no = 
+?");

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From the error message, it seems like you are assigning RESULTS with something like SELECT.

In reply to Re^3: DBI place holder for sub query problem by olus
in thread DBI place holder for sub query problem by Anonymous Monk

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