Question

我创建了一个像这样的查询

 "select count(if(gender="male",1,null)) as malecount,
  count(if(gender="female",1,null)) as femalecount from biodata"

这是工作，我想总结这样的计数：

 "select count(if(gender="male",1,null)) as malecount,
  count(if(gender="female",1,null)) as femalecount, male+female as sumgender 
  from biodata"

当我在if语句中提出许多条件时，查询将有所帮助

请帮我解决这个案子......

Answer 1

要么

select 
count(if(gender="male",1,null)) as malecount,
count(if(gender="female",1,null)) as femalecount, 
count(if(gender in ("female","male",1,0)) as sumgender 
from biodata

或者如果您确定所有行都有男性或女性作为性别，请使用简单的计数（1）

select 
count(if(gender="male",1,null)) as malecount,
count(if(gender="female",1,null)) as femalecount, 
count(1) as sumgender 
from biodata

或做一个子查询

select
malecount, 
femalecount,
malecount + femalecount as sumgender
from (
select 
count(if(gender="male",1,null)) as malecount,
count(if(gender="female",1,null)) as femalecount
from biodata
) sub

但您无法使用聚合别名在同一个选择中进行计算。

Answer 2

用这种方式解决问题

select malecount+femalecount as sumcount from  (select
count(if(gender="male",1,null)) as malecount,  
 count(if(gender="female",1,null)) as femalecount   from biodata) as
 query

总结初始列mysql

2 个答案: