计算单个查询中的布尔字段值

Question

我喜欢获得某个字段为1或0的行数.

我的表看起来像这样:

ID | name | my_bool
===================
 1 | foo  | 1
 2 | bar  | 1
 3 | loo  | 0
 4 | zoo  | 1

结果我期待

YES | NO  | percentage
======================
 3  | 1   | 0.3333

YES是多少行my_bool是真(1)而NO行是假(0)

percentage给出的百分比YES来NO

Answer 1

在MySQL中,您可以使用条件聚合轻松完成此操作:

select sum(my_bool = 1) as yes, sum(my_bool = 0) as no
from table t;

编辑:

百分比很简单:

select sum(my_bool = 1) as yes, sum(my_bool = 0) as no, avg(my_bool = 0)
from table t;

但是,您的价值表明您正在寻找比率,而不是百分比.为此,你需要注意除以零:

select sum(my_bool = 1) as yes, sum(my_bool = 0) as no,
       (case when sum(my_bool = 1) > 0 then sum(my_bool = 0) / sum(my_bool = 1)
        end)
from table t;