MySQL:检索每个的唯一值和计数

Question

是否有一种简单的方法可以检索列中所有唯一值的列表,以及该值出现的次数？

示例数据集:

A
A
A
B
B
C

......会回来:

A  |  3
B  |  2
C  |  1

谢谢!

Answer 1

使用GROUP BY:

select value, count(*) from table group by value

使用HAVING进一步减少结果,例如只发生超过3次的值:

select value, count(*) from table group by value having count(*) > 3

Answer 2

SELECT id,COUNT(*) FROM file GROUP BY id