Question

这是电影表： movies table

这是查询的结果表： results table

查询：

SELECT DISTINCT m.movieID, m.title,s.scheduleDateTime, tf.theaterFeatureID, s.scheduleID, m.releasedDate
FROM theater_feature AS tf 
LEFT JOIN schedule AS s ON s.theaterFeatureID = tf.theaterFeatureID 
INNER JOIN movie AS m ON tf.movieID = m.movieID 
WHERE (s.scheduleDateTime > '2014-10-24' OR s.scheduleDateTime IS NULL)
    AND (tf.theaterFeatureID 
        NOT IN ( SELECT s1.theaterFeatureID FROM schedule AS s1 
                WHERE s1.theaterFeatureID = tf.theaterFeatureID 
                AND s1.scheduleDateTime <= '2014-10-24') )
ORDER BY m.releasedDate, s.scheduleDateTime

我在简化此查询时遇到问题，因为它太慢了。它的作用是：

它会在特定日期显示带有时间表的电影（但不是当前或尚未过去的电影，在此示例中，它是＆＃39; 2014-10-24＆＃39;），以及如果电影尚未安排（或为空），则也应包括它。
但是，如果电影通过了第一个资格（电影的日程安排在＆＃39; 2014-10-24＆＃39;，或者电影还没有时间表或IS NULL），但是有一个在已经过去的日期安排，该电影不应被包括在内。简而言之，查询是为了即将推出的电影。

在表格中，电影＆＃34;地图到星星＆＃34;和＃34; The Maze Runner＆＃34;因为它们具有已经过去的计划，所以不包括在结果表中。查询已经很好但我想简化它，如果可能的话，替换NOT IN。

我知道这听起来很复杂，但我真的需要弄清楚这一点。如果有人可以帮助我，我真的很感激。

Answer 1

查看ID是否存在而不是NOT IN。

而不是：

 NOT IN ( SELECT s1.theaterFeatureID FROM schedule AS s1 
                WHERE s1.theaterFeatureID = tf.theaterFeatureID 
                AND s1.scheduleDateTime <= '2014-10-24')

执行：

 NOT EXISTS( SELECT s1.theaterFeatureID FROM schedule AS s1 
                WHERE s1.theaterFeatureID = tf.theaterFeatureID 
                AND s1.scheduleDateTime <= '2014-10-24')

编辑完整查询，为清晰起见

SELECT DISTINCT m.movieID, m.title,s.scheduleDateTime, 
                tf.theaterFeatureID, s.scheduleID, m.releasedDate
FROM theater_feature AS tf 
       LEFT JOIN schedule AS s ON s.theaterFeatureID = tf.theaterFeatureID 
       INNER JOIN movie AS m ON tf.movieID = m.movieID 
    WHERE s.scheduleDateTime > '2014-10-24'
         AND NOT EXISTS ( SELECT s1.theaterFeatureID FROM schedule AS s1 
                WHERE s1.theaterFeatureID = tf.theaterFeatureID 
                AND s1.scheduleDateTime <= '2014-10-24') 
    ORDER BY m.releasedDate, s.scheduleDateTime

在正在查询的列上添加索引也可能会有所帮助。

Answer 2

SELECT DISTINCT m.movieID, m.title,s.scheduleDateTime, tf.theaterFeatureID, s.scheduleID, m.releasedDate
FROM theater_feature AS tf 
LEFT JOIN schedule AS s ON s.theaterFeatureID = tf.theaterFeatureID 
INNER JOIN movie AS m ON tf.movieID = m.movieID 
WHERE s.scheduleDateTime > '2014-10-24'
ORDER BY m.releasedDate, s.scheduleDateTime

为什么你使用NOT IN条件，它已经使用这个条件获得那些大于日期时间的数据WHERE s.scheduleDateTime > '2014-10-24'

Answer 3

我建议两件事：

不要使用DISTINCT;在您的测试数据中，这似乎没有必要
在schedule.scheduleDateTime
上添加索引
CREATE INDEX ix_scheduleDateTime ON schedule（scheduleDateTime）

然后，以下任何一个都会产生相同的结果（来自sqlfiddle的测试数据）：

SELECT
      m.movieID
    , m.title
    , s.scheduleDateTime
    , tf.theaterFeatureID
    , s.scheduleID
    , m.releasedDate
FROM theater_feature AS tf
      LEFT JOIN schedule AS s
                  ON s.theaterFeatureID = tf.theaterFeatureID
      INNER JOIN movie m
                  ON tf.movieID = m.movieID
WHERE (s.scheduleDateTime > '2014-10-24'  OR s.scheduleDateTime IS NULL)
      AND tf.theaterFeatureID
          NOT IN (
                SELECT
                      s1.theaterFeatureID
                FROM schedule AS s1
                WHERE s1.theaterFeatureID = tf.theaterFeatureID
                      AND s1.scheduleDateTime <= '2014-10-24'
          )
ORDER BY
      m.releasedDate, s.scheduleDateTime
;

SELECT
      m.movieID
    , m.title
    , s.scheduleDateTime
    , tf.theaterFeatureID
    , s.scheduleID
    , m.releasedDate
FROM theater_feature AS tf
      LEFT JOIN schedule AS s
                  ON s.theaterFeatureID = tf.theaterFeatureID
      INNER JOIN movie AS m
                  ON tf.movieID = m.movieID
WHERE (s.scheduleDateTime > '2014-10-24'  OR s.scheduleDateTime IS NULL)
      AND NOT EXISTS (
            SELECT NULL
            FROM schedule AS s1
            WHERE s1.theaterFeatureID = tf.theaterFeatureID
                  AND s1.scheduleDateTime <= '2014-10-24'
      )
ORDER BY
      m.releasedDate, s.scheduleDateTime
;

在sqlfiddle，执行计划看起来相同

简化NOT IN查询

3 个答案: