mysql - 如何在 mysql 上分隔 bool 列值

Question

我有这张 table

create table votes(
    candidate varchar(20),
    voteup bool
)

我想显示这样的东西

|candidate|vote ups(true)|vote downs(false)|vote points(true-false)
|hitler   |16            |104              |-88
|obama    |119           |1                |118

Answer 1

您可以“滥用” bool 值在整数运算中计算为 1 和 0 的事实:

select candidate,
    sum(voteup) as 'vote up',
    sum(voteup=0) as 'vote down',
    sum(if(voteup,1,-1)) as 'vote points'
from votes
group by candidate;