4-2 [MySQL] 如何计算累进税

select a.user_name,money,low,high,rate from user1 a join taxRate b on a.money>b.low order by user_name;

select a.user_name,money,low,high, least(monwy-low,high-low) as curmoney ,rate from user1 a join taxRate b on a.money>b.low order by user_name,low;

4-1 [MySQL] 计算累进税需求分析


3-5 [MySQL] 使用Group by 实现多属性查询

3-3 [MySQL] 使用关联方式实现多属性查询(一)

3-2 [MySQL] 什么是同一属性的多值过滤

select a.user_name,b.skill,b.skill_level
from user1 a join user1_skills b on a.id=b.user_id
where skill in ('变化','念经') and skill_level>0;
select a.user_name,b.skill,c.skill from user1 a
join user1_skills b on a.id=b.user_id and b.skill='变化'
join user1_skills b on a.id=b.user_id and b.skill='念经'
where b.skill_level>0 and c.skill_level>0;
3-1 实例场景说明

2-2 [MySQL] 如何在子查询中实现多列过滤

select a.user_name,b.timestr,kills from user1 a join user_kills b on a.id = b.user_id join (select user_id,max(kills) as cnt from user_kills group by user_id) c on b.user_id = c.user_id and b.kill=c.cnt;

2-1 [MySQL] 子查询的使用场景及其好处


1-1 内容介绍

使用LEAST区间函数,计算累计纳税

Group同一属性的多值过滤

计算累进税
2)算出总的纳税额度

计算累进税
1)算出每个计税区间中所应纳税额度

使用group by方法解决同一属性的多值过滤
left join和case语句实现多属性查询
使用join实现同一属性的多值过滤
同一属性的多值过滤,查询出同时具有变化和念经这两项技能的经纪人
mysql中独有的多列过滤方式(大于1列)
备注:子查询效率低,最好还是使用连接查询

在子查询中实现多列过滤
least
MySQL---独有的多例过滤方式
SELECT a.user_name,b.timerstr,kills FROM user1 a JOIN user_kills b ON a.id=b.user_id WHERE(b.user_id,b.kills) IN( SELECT user_id,MAX(kills)
查找表中多余的重复记录(多个字段)
select * from vitae a where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)
什么是子查询
good?????
同一属性的多值过滤,使用group by 或者 join join join 
in条件相当于几个()里边几个or

同时具有念经和变化的取经人