As noted above, you call

  $dbh->do("update table set thing = ? where id = ?",
            \%attr, $thing, $id);
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What you pass in \%attr is interesting and not particularly obvious, though. Provided you don't want to pass any attributes (I've never needed to) you can pass undef or { } whichever takes your fancy. Eg :-

  $dbh->do("update table set thing = ? where id = ?",
            undef, $thing, $id);
  # OR
  $dbh->do("update table set thing = ? where id = ?",
            {}, $thing, $id);
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I usually encapsulate it in a little function though so I can just print out the values of the updates in debug mode!