這個MYSQL查詢有什么問題

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)));

這在Toad / MYsql中工作正常，但是當我使用Java + mysql驅動程序中的預處理語句執行此操作時失敗

    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

它與問題沒有密切關系，但查詢效率不高，可以改進

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 

你需要索引

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