Assuming you are using the DBI module, you can use "trace" to see the query that is actually being sent to the database. Do

   perldoc DBI
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at a command prompt to read the excellent documentation that is included with the DBI module. Search(using the forward slash "/") for the word "trace".

The basic idea is to turn trace on before the statements you are interested in, and turn it off after - something like this:

   $sql="Select * from table where column=?";
   DBI->trace(2); # turn trace on
   $rh=$dbh->prepare($sql);
   $rh->execute($str);
   DBI->trace(0); # turn trace off
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HTH.