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Try this. It doesn't appear to impact performance. Unmodified : 2987 rows in set (1.53 sec) Modified : 2987 rows in set (1.48 sec) I had to use GROUP BY to get a single row with 1234 1 1 otherwise, if both matched, it gave 1234 1 0 1234 0 1 Query SELECT id , SUM(match_email) as by_email , SUM(match_phone) as by_phone FROM ( SELECT `a1`.`id`, 1 as match_email, 0 as match_phone FROM ( ( `customers` `a1` JOIN `customers` `b1` ON ( ( (`a1`.`email` = `b1`.`email`) AND(`a1`.`id` <> `b1`.`id`) AND( `a1`.`email` <> 'blah@example.com' ) AND( `b1`.`email` <> 'blah@example.com' ) ) ) ) JOIN `quotes` `q1` ON ( ( (`q1`.`customer_id` = `b1`.`id`) AND(`q1`.`purchased` = 1) ) ) ) UNION SELECT `a`.`id`, 0 as match_email, 1 as match_phone FROM ( ( `customers` `a` JOIN `customers` `b` ON ( ( (`a`.`phone` = `b`.`phone`) AND(`a`.`id` <> `b`.`id`) ) ) ) JOIN `quotes` `q` ON ( ( (`q`.`customer_id` = `b`.`id`) AND(`q`.`purchased` = 1) ) ) ) ) all_matches GROUP BY `id`