这个 MYSQL 查询有什么问题

Question

    SELECT * FROM event JOIN user ON event.event_user_id=user.user_id
  WHERE ((event.event_date BETWEEN '2011-03-01' AND '2011-04-01' ) 
    AND user.user_id in (SELECT user_id FROM user_map 
      WHERE (user_map.user_id_map=1 AND user_map.user_relation<=7)));

这在 Toad/MYsql 中工作正常，但当我使用 java + mysql 驱动程序中的准备好的语句执行此操作时失败

    SELECT * FROM event JOIN user ON event.event_user_id=user.user_id
  WHERE ((event.event_date BETWEEN ? AND ? ) 
    AND user.user_id in (SELECT user_id FROM user_map 
      WHERE (user_map.user_id_map=? AND user_map.user_relation<=?)));

...

pstmt.setDate(1, <sqlDate>);
pstmt.setDate(2, <sqlDate>);
pstmt.setLong(3, <int>);
pstmt.setLong(4, <int>);

pstmt.executeQuery();

Answer 1

它与问题没有密切关系，但查询效率不高，可以改进，

SELECT * 
FROM   event 
       JOIN USER 
         ON event.event_user_id = USER.user_id 
       JOIN user_map 
         ON user_map.user_id = USER.user_id 
            AND user_map.user_id_map = 1
            AND user_map.user_relation<=7 
WHERE  ( event.event_date BETWEEN '2011-03-01' AND '2011-04-01' ) 
GROUP  BY USER.user_id 

您需要

• (event.event_user_id,event.event_date)
• (USER.user_id)
• (user_map.user_id, user_map.user_id_map,user_map.user_relation)上的索引