0

当我尝试将两个子查询连接在一起时，第一个查询中的值发生了变化。知道为什么吗？谢谢！

这是代码：

SELECT *
FROM    ((

     SELECT HOME, VISITOR, COUNT("result") AS HGOALS
     FROM(
         SELECT HOME, VISITOR, "result"
         FROM ENGLAND
         WHERE TIER = 1 AND "SEASON" >= 1980 AND "result" = 'H'
         )
     GROUP BY HOME, VISITOR
     ORDER BY HGOALS DESC)
             JOIN
     (SELECT HOME, VISITOR, COUNT("result") AS AGOALS
     FROM(
         SELECT HOME, VISITOR, "result"
         FROM ENGLAND
         WHERE TIER = 1 AND "SEASON" > 1980 AND "result" = 'A'
         )
     GROUP BY HOME, VISITOR) USING (VISITOR, HOME))
     ORDER BY AGOALS DESC;

输出的部分是

     Manchester United  Aston Villa 5   18
     Arsenal    West Ham United 5   17
     Arsenal    Aston Villa 6   17
     Manchester United  Everton 12  16
     Liverpool  Aston Villa 8   16

但是当我只执行 JOIN 的第一部分时，即

     SELECT HOME, VISITOR, COUNT("result") AS HGOALS
     FROM(
         SELECT HOME, VISITOR, "result"
         FROM ENGLAND
         WHERE TIER = 1 AND "SEASON" >= 1980 AND "result" = 'H'
         )
     GROUP BY HOME, VISITOR
     ORDER BY HGOALS DESC

结果的一部分是：

     Manchester United  Tottenham Hotspur   27
     Arsenal    Everton 26
     Manchester United  Aston Villa 26
     Liverpool  Tottenham Hotspur   25
     Manchester United  West Ham United 24

请注意，对于

     Manchester United  Aston Villa 5   18
     Manchester United  Aston Villa 26

我应该得到的结果是 26，但是当我将两个子查询连接在一起时它变成了 5。为什么？

4

1 回答 1

0

我的问题很复杂。这不是你想要的吗？

SELECT HOME, VISITOR,
       SUM(CASE WHEN result = 'H' THEN 1 ELSE 0 END) as HGOALS,
       SUM(CASE WHEN result = 'A' THEN 1 ELSE 0 END) as AGOALS
FROM ENGLAND
WHERE TIER = 1 AND SEASON >= 1980 
GROUP BY HOME, VISITOR
ORDER BY AGOALS DESC;

注意：您可能需要在 周围加上引号result，具体取决于列的定义方式。

于 2017-10-15T22:23:12.013 回答