sql学习-with as的使用-分析数据得到结果

Posted 2022-08-01 许佳佳233

概述

当前有一张“学生成绩表”
需要查询男女的及格率。

例子

create table StudentScore (
 name string,
 score int,
 sex string
);

INSERT INTO StudentScore VALUES
('AAA',32,'man'),
('BBB',58,'man'),
('CCC',82,'man'),
('DDD',44,'woman'),
('EEE',92,'woman');

select查询

with as作用：
定义一个SQL片断，该SQL片断会被整个SQL语句所用到。
不仅可以提高代码的可读性，也可以提高代码的复用性。

with
tmp_sex_count as (
    select count(1) as count_all,sex
    from StudentScore
    group by sex
),
tmp_sex_score as(
    select count(1) as count_0_60
    ,sex
    from StudentScore
    where score<60
    group by sex
)
select tmp_sex_count.sex as sex
,count_0_60
,count_all 
,count_0_60*100/count_all as percent_0_60
from tmp_sex_count
join tmp_sex_score on tmp_sex_score.sex=tmp_sex_score.sex;

查询结果

man|2|3|66
woman|2|2|100
man|1|3|33
woman|1|2|50