just an FYI:
those suggestion lanjoky will only be necessary if, and only if, register_globals = Off
and i believe that the way you have the query would make it choke also, you have your $row['vars'] inside single quotes, that isn't gonna work
what i suggest is either to hop in and out (concatenation) of the quoted string, or set $variable = $row['variable'];
then you can use it single ticked in your query