The only occurance of execute in the script is

$sth->execute ||
   die "Could not execute SQL statement ... " . $dbh->errstr;
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I hope this is line 51.

This seems a bit odd to me, as you ought to be finding that error string in the log file. But the implication is clearly that $sth is undefined. The only way this can be happening is if the prepare on the previous line has failed. And you're not error trapping that.

(I no nothing about odbc, but the line if     ($where_clause) in the middle of the sql statement looks odd to me)

And I'm confused about the error trapping anyway: you've set RaiseError to 1, so every statement ought to be error trapped by DBI anyway. Which would explain why you don't see the "Could not execute SQL statement" in the log: DBI has died before your code gets a chance to. But it doesn't explain why the prepare doesn't result in death. Odd.

--
Tommy
Too stupid to live.
Too stubborn to die.