sql error displayed when going to Users Management tab (backend)

I get the following error displayed when going to CB > User Management.

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 ') or cb_branchname2 = (SELECT CONCAT(firstname, ', ', lastname) FROM hr972_compr' at line 1 SQL=SELECT CONCAT('<a href="',REPLACE(REPLACE(firstname,'\'',''),' ','-'),'-',(REPLACE(lastname,'\'','')),'"/>',firstname,' ',lastname,'</a>') AS mysqlfield FROM hr972_comprofiler WHERE (cb_branchname1 = (SELECT CONCAT(firstname, ', ', lastname) FROM hr972_comprofiler WHERE user_id = ) or cb_branchname2 = (SELECT CONCAT(firstname, ', ', lastname) FROM hr972_comprofiler WHERE user_id = ) or cb_branchname3 = (SELECT CONCAT(firstname, ', ', lastname) FROM hr972_comprofiler WHERE user_id = )) and approved = 1 ORDER BY firstname ASC

Looks like you've an error in your CB Query Field usage. You need to edit your query field and find your [user_id] usage then surround it with single quotes (e.g. '[user_id]'). Always treat substitutions as strings.