php/mysql - 比较 2 个表中的多个列并显示最大差异

Question

我有 1 个包含我所有信息的主表和 1 个结构几乎相同但值略有不同的表。现在我想比较这些值并获得最大差异。我对每列(a1-a5)进行查询，并在每个查询的循环中再次查询并对结果进行一些计算...我不知道，它很困惑，我不知道如何得到这个以干净的方式。

这是两个表的结构:

+----------+----------+--------+-----+-----+-----+-----+-----+--------------+
| HomeTeam | AwayTeam | Result |  a1 |  a2 |  a3 |  a4 |  a5 |  Date        |
+----------+----------+--------+-----+-----+-----+-----+-----+--------------+
| team1    | team2    |      H |  5  |  2  |  4  |  4  |  3  |  11-04-2017  |
| team3    | team4    |      A |  6  |  8  |  4  |  2  |  6  |  11-04-2017  |
| team1    | team3    |      D |  3  |  7  |  9  |  7  |  2  |  12-04-2017  |
| team4    | team2    |      H |  2  |  4  |  8  |  6  |  5  |  12-04-2017  |
+----------+----------+--------+-----+-----+-----+-----+-----+--------------+

+----------+----------+-----+-----+-----+-----+-----+
| HomeTeam | AwayTeam |  a1 |  a2 |  a3 |  a4 |  a5 |
+----------+----------+-----+-----+-----+-----+-----+
| team1    | team2    |  2  |  3  |  5  |  3  |  3  |
| team3    | team4    |  5  |  7  |  5  |  2  |  3  |
| team1    | team3    |  4  |  2  |  8  |  6  |  5  |
| team4    | team2    |  2  |  5  |  5  |  6  |  4  |
+----------+----------+-----+-----+-----+-----+-----+

这就是我想要打印的内容:

team 1 vs team 2 biggest increase was 150% (a1 -> 5 vs 2) on 11-04-2017 
team 3 vs team 4 biggest increase was 100% (a5 -> 6 vs 3) on 11-04-2017 
team 1 vs team 3 biggest increase was 250% (a2 -> 7 vs 2) on 12-04-2017 
team 4 vs team 2 biggest increase was 60% (a3 -> 8 vs 5) on 12-04-2017 

当我输入此内容时，我想也许只使用一个查询来获取两个表中的所有内容并使用这些值进行一些计算？不确定..有人可以在正确的方向上给我很大的帮助，告诉我如何做到这一点？

Answer 1

我们可以在这里使用 GREATEST 来查找每场比赛的最大差价:

SELECT
    HomeTeam,
    AwayTeam,
    GREATEST(t1.a1 - t2.a1, t1.a2 - t2.a2, t1.a3 - t2.a3, t1.a4 - t2.a4, t1.a5 - t2.a5) AS max_diff
FROM table1 t1
INNER JOIN table2 t2
    ON t1.HomeTeam = t2.HomeTeam AND t1.AwayTeam = t2.AwayTeam;

如果您还想要实际的 a 值，那么这将需要更多的工作，特别是考虑到您的数据未标准化。您可能需要对比上述更复杂的数据进行标准化。