ユーザーテーブルとユーザー属性テーブルが存在し、属性を条件としたユーザーの絞り込みを行いたい場合のSQL

users

+-------------+--------------+------+-----+---------+----------------+
| Field       | Type         | Null | Key | Default | Extra          |
+-------------+--------------+------+-----+---------+----------------+
| id          | int(11)      | NO   | PRI | NULL    | auto_increment |
| name        | varchar(20)  | NO   |     | NULL    |                |
+-------------+--------------+------+-----+---------+----------------+

user_attributes

+-------------+--------------+------+-----+---------+----------------+
| Field       | Type         | Null | Key | Default | Extra          |
+-------------+--------------+------+-----+---------+----------------+
| id          | int(11)      | NO   | PRI | NULL    | auto_increment |
| user_id     | int(11)      | NO   |     | NULL    |                |
| attr_key    | varchar(20)  | NO   |     | NULL    |                |
| attr_value  | varchar(255) | NO   |     | NULL    |                |
+-------------+--------------+------+-----+---------+----------------+

SELECT * FROM users
WHERE id IN (
  SELECT user_id FROM user_attributes
  WHERE 0 OR
    (attr_key = 'blood_type' AND attr_value = 'A') OR
    (attr_key = 'pref_code' AND attr_value = '13')
  GROUP BY user_id
  HAVING COUNT(*) = 2
);