[英]How to group sums by weekday in MySQL?
我有这样一张桌子:
id | timestamp | type
-----------------------
1 2010-11-20 A
2 2010-11-20 A
3 2010-11-20 B
4 2010-11-21 A
5 2010-11-21 C
6 2010-11-27 B
我需要计算每种类型的行数,按工作日分组; 像这样:
weekday | A | B | C
--------------------------
5 2 2 0 -- the B column equals 2 because nov 20 and nov 27 are saturday
6 1 0 1
对此最简单的解决方案是什么?
我不介意使用视图,变量,子查询等。
使用:
SELECT WEEKDAY(t.timestamp) AS weekday,
SUM(CASE WHEN t.type = 'A' THEN 1 ELSE 0 END) AS a,
SUM(CASE WHEN t.type = 'B' THEN 1 ELSE 0 END) AS b,
SUM(CASE WHEN t.type = 'C' THEN 1 ELSE 0 END) AS c
FROM YOUR_TABLE t
GROUP BY WEEKDAY(t.timestamp)
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