如何在mysql中进行计数

Question

我有一个“用户”的表

我想计算他们有1和2的工资

我如何在mysql中计算

Answer 1

查看Aggregate Functions in MySQL和GROUP BY (Aggregate) Functions

Answer 2

获得两者的总薪水

SELECT SUM(salary) FROM users WHERE id IN(1, 2);

并获得个人工资总额

SELECT SUM(salary) FROM users WHERE id IN(1, 2) group by id;

Answer 3

SELECT SUM(salary) FROM users WHERE id IN(1, 2);

Answer 4

我将引用您来计算mysql documentation

中的行数

可能就像：

SELECT COUNT(*) FROM users WHERE id IN (1,2);

虽然如果你真的想要总结工资，那么你应该参考group by functions

SELECT id, SUM(salary) FROM users WHERE id IN (1,2) GROUP BY id;