[GTLS]

Код:

 new query[60];
format(query, sizeof(query), "UPDATE `playerdata` SET `pjobselected` = 1 WHERE = SOMETHING HERE...");
mysql_tquery(dbHandle, query);

Problem was your size of query. If you had posted MySQL Logs, it would show you that Query is empty because destination array is too small. Query was size of 24 while clearly, there are more than 24 characters.