mysql - 获取客户行的总和

Question

如何获得每个客户的工作时间总和？ 我的数据看起来像这样

  Customer  |   Hours
   C1       |    15
   C1       |    13
   C3       |    23
   C4       |    10
   C4       |    5

Customer 和 Hours 在单独的表中。 我是这样查询的:

SELECT DISTINCT t2.Customer
FROM table1 t1
LEFT JOIN table2 t2
ON t1.id = t2.id
WHERE t2.Customer is not null
ORDER BY t2.Customer ASC

结果是

Customer
C1
C3
C4

我接下来要做的是对客户的工作时间求和，这样输出将如下所示:

Customer   |    Hours
C1         |    28
C3         |    23
C4         |    15

Answer 1

你想要一个group by语句，像这样:

SELECT t2.Customer, sum(t1.hours) as hours
FROM table1 t1 LEFT JOIN
     table2 t2
     ON t1.id = t2.id
WHERE t2.Customer is not null
GROUP BY t2.Customer
ORDER BY t2.Customer ASC;