Generic Error - MySQL

MySQL Code

SELECT * FROM ac_poem_text WHERE poem_active = 1 AND poet_id =

MySQL Result

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1

MySQL File

LINE:64
FILE:classes.php

BACKTRACE

FILE: includes/database.php
LINE: 44
CALL: db->debug_mode()

FILE: includes/classes.php
LINE: 65
CALL: db->query()

FILE: diwan.php
LINE: 115
CALL: DIWAN_CLASS->get_total_poems()