sql – 如何将行转移到列中(自定义透视)

Day   Period    Subject

Mon   1         Ch
Mon   2         Ph
Mon   3         Mth
Mon   4         CS
Mon   5         Lab1
Mon   6         Lab2
Mon   7         Lab3
Tue   1         Ph
Tue   2         Ele
Tue   3         Hu
Tue   4         Ph
Tue   5         En
Tue   6         CS2
Tue   7         Mth

我希望它显示如下：种类的交叉表或枢轴

Day   P1   P2   P3   P4   P5   P6   P7

Mon   Ch   Ph   Mth  CS2  Lab1 Lab2 Lab3
Tue   Ph   Ele  Hu   Ph   En   CS2  Mth

这样做的理想方式是什么？有人可以给我看一下Sql代码吗？

解决方法

SELECT
    dy,MAX(CASE WHEN period = 1 THEN subj ELSE NULL END) AS P1,MAX(CASE WHEN period = 2 THEN subj ELSE NULL END) AS P2,MAX(CASE WHEN period = 3 THEN subj ELSE NULL END) AS P3,MAX(CASE WHEN period = 4 THEN subj ELSE NULL END) AS P4,MAX(CASE WHEN period = 5 THEN subj ELSE NULL END) AS P5,MAX(CASE WHEN period = 6 THEN subj ELSE NULL END) AS P6,MAX(CASE WHEN period = 7 THEN subj ELSE NULL END) AS P7
FROM
    Classes
GROUP BY
    dy
ORDER BY
    CASE dy
        WHEN 'Mon' THEN 1
        WHEN 'Tue' THEN 2
        WHEN 'Wed' THEN 3
        WHEN 'Thu' THEN 4
        WHEN 'Fri' THEN 5
        WHEN 'Sat' THEN 6
        WHEN 'Sun' THEN 7
        ELSE 8
    END

>我更改了一些列名以避免使用保留字

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