> What's a module to do when it recieves two calls to hook_db_rewrite_sql;
> in
> both cases $primary_field is 'cid' and $primary_table is 'c', but in one
> case
> the query needs re-writing and in the other it does not?
You could, awkwardly, test the full $query for your table's name and alias,
e.g.
if (strstr($query, '{category} c')) {
}