how to make counting in mysql

i have a table that "users"

i want to count their salary who have开发者_如何学编程 ID 1 and 2

how i can count this in mysql

Have a look at Aggregate Functions in MySQL and GROUP BY (Aggregate) Functions

to get total salary of both

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

and to get individual sum of salary

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

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

I shall refer you to counting rows from the mysql documentation

probably goes like:

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

although if you're actually trying to sum the salaries then you should refer to group by functions

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