SQL info: MySQL Query Error

Time: 2017-12-12 10:32am
Script: /user/index.php

SQL: SELECT * FROM User_Identity AS i LEFT JOIN User_Datum AS u ON i.UserID=u.UserID WHERE i.UserID=
Error: 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
Errno.: 1064