simple sql query is failing

You could print out last DB query and any errors right after query call and see what it actually tried to run:

PHP Code:

$result = $this->db->query($sql);
echo $this->db->last_query();
echo $this->db->error(); 


You have to make sure database configuration has save_queries set to true.

Thanks. I have it enabled but where is the last query stored?

proof that an old dog can learn new tricks