mysql> EXPLAIN select n.email, n.type from NWR_Database n, CandidatesList c where n.email = c.email and n.type IN ('CONTRACT','ADHOC CONTRACT') and c.preference IN ('SAP','ORACLE','ORACLE CLINICALS','ORACLE DBA','ORACLE DEVELOPER','ORACLE FINANCIALS','ERP','ERP/CRM/BAAN/PSOFT/JDE','CRM','UNIX','UNIX ADMINISTRATOR','SIEBEL');
+----+-------------+-------+------+---------------+-------+---------+-----------------+---------+-------------+
| id | select_type | table | type | possible_keys | key   | key_len | ref             | rows    | Extra       |
+----+-------------+-------+------+---------------+-------+---------+-----------------+---------+-------------+
|  1 | SIMPLE      | c     | ALL  | NULL          | NULL  | NULL    | NULL            | 1929377 | Using where | 
|  1 | SIMPLE      | n     | ref  | Email         | Email | 767     | ITMedia.c.Email |       1 | Using where | 
+----+-------------+-------+------+---------------+-------+---------+-----------------+---------+-------------+
2 rows in set (0.00 sec)