如何在mysql中按分区获取每组的行数？

Question

In mysql, if you have a table like this

A | B
------
1 | 0
1 | 0
1 | 0
2 | 0
2 | 0
3 | 0
3 | 0
3 | 0
3 | 0

How can you turn it into

A | c
------
1 | 3
2 | 2
3 | 4

c is the count column, so there was 3 1's, 2 2's and 4 3's.

Does anyone know how to do this?

Thanks.

Answer 1

You can do it like this:

SELECT A, count(*) as c FROM table GROUP BY A;

check this SQLFiddle to play around with it: http://sqlfiddle.com/#!2/36c59/1

Answer 2

     select count(A) from table group by A;