2020-07-26

凯莉的日记

于 2020-07-26 18:30:18 发布

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分类专栏：笔记

本文链接：https://blog.youkuaiyun.com/m0_49523665/article/details/107597519

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#一、查询分组函数
select max(salary) from employees;
select min(salary) from employees;
select avg(salary) from employees;
select count(salary) from employees;
select sum(salary) from employees;
select max(salary),sum(salary) from employees;
#二、关于sum 和avg
select avg(first_name) from employees;
select sum(first_name) from employees;
selectsum(commission_pct)/count(*),avg(commission_pct)from employees;
#三、关于max和min
select max(first_name),min(first_name) from employees;
select max(commission_pct),min(commission_pct) from employees;
#四、关于count
select count(DISTINCT department_id) from employees;
select count(commission_pct) from employees;