mysql - 如何对多行求和？

Question

我有一个这样的表:'round' 是一种 id

id  round  kind   count
1     1     1      10
1     1     2      10
1     1     1      20
1     2     1      10
1     2     1      30
2     1     1      15
2     1     1      10
2     2     2      20

我想要这些结果

id  round  kind1Total  kind2Total   roundTotal
1     1    30           10            40
1     2    40                         40
2     1    25                         25
2     2                 20            20

Answer 1

使用条件聚合:

SELECT
    id,
    round,
    SUM(IF(kind=1, count, 0)) AS kind1Total,
    SUM(IF(kind=2, count, 0)) AS kind2Total,
    SUM(count) AS roundTotal
FROM yourTable
GROUP BY
    id,
    round
ORDER BY
    id,
    round;