select
count(*) as 人口总数,
sum(case when sex=0 then 1 else 0 end) 男人数,
sum(case when sex=0 then 1 else 0 end)/count(*)男所占比例,
sum(case when sex=1 then 1 else 0 end) 女人数,
sum(case when sex=1 then 1 else 0 end) /count(*)女所占比例
from cj_yonghu
count(*) as 人口总数,
sum(case when sex=0 then 1.00 else 0.00 end) 男人数,
sum(case when sex=0 then 1.00 else 0.00 end)/count(*)男所占比例,
sum(case when sex=1 then 1.00 else 0.00 end) 女人数,
sum(case when sex=1 then 1.00 else 0.00 end) /count(*)女所占比例
from cj_yonghu
select
count(*) as 人口总数,
sum(case when sex=0 then 1 else 0 end) 男人数,
sum(case when sex=0 then 1 else 0 end)*1.0/count(*)男所占比例,
sum(case when sex=1 then 1 else 0 end) 女人数,
sum(case when sex=1 then 1 else 0 end)*1.0 /count(*)女所占比例
from cj_yonghu
select
count(*) as 人口总数,
sum(case when sex=0 then 1 else 0 end) 男人数,
1.0*sum(case when sex=0 then 1 else 0 end)/count(*) 男所占比例, --加上1.0,否则整数/整数取的还是整数
sum(case when sex=1 then 1 else 0 end) 女人数,
1.0*sum(case when sex=1 then 1 else 0 end)/count(*) 女所占比例
from cj_yonghu
select
count(*) as 人口总数,
sum(case when sex=0 then 1 else 0 end) 男人数,
cast(100.0*sum(case when sex=0 then 1 else 0 end)/count(*) as varchar(20))+'%' 男所占比例, --加上1.0,否则整数/整数取的还是整数
sum(case when sex=1 then 1 else 0 end) 女人数,
cast(100.0*sum(case when sex=1 then 1 else 0 end)/count(*) as varchar(20))+'%' 女所占比例
from cj_yonghu
select
count(*) as 人口总数,
sum(case when sex=0 then 1 else 0 end) 男人数,
cast(1.0*sum(case when sex=0 then 1 else 0 end)/count(*) as varchar(20))+'%' 男所占比例, --加上1.0,否则整数/整数取的还是整数
sum(case when sex=1 then 1 else 0 end) 女人数,
cast(1.0*sum(case when sex=1 then 1 else 0 end)/count(*) as varchar(20))+'%' 女所占比例
from cj_yonghu
select sClass 班级,count(*) 班级学生总人数, sum(case when sGender=0 then 1 else 0 end) 女生人数, sum(case when sGender=0 then 1 else 0 end)*1.0/count(*)女生所占比例, sum(case when sGender=1 then 1 ...
select sClass 班级,count(*) 班级学生总人数,sum(case when sGender=0 then 1 else 0 end) 女生人数,sum(case when sGender=0 then 1 else 0 end)*1.0/count(*)女生所占比例,sum(case when sGender=1 then 1 else 0...
/*=================表操作===================*/ --创建用户设置密码 create user tianhp identified by 237219; --授权 grant connect,resource to tianhp;...studentName varchar2(1
查询语句语法 SELECT [ALL | DISTINCT] select_expr, select_expr,... FROM table_reference [WHERE where_condition] [GROUP BY col_list] [ORDER BY col_list] [CLUSTER BY col_list | [DISTRIBUTE BY ...