belldeep的专栏

SQL left join , right join , full outer join

## 基金净值：求月平均值select month(date1) as "月份", min(jz) as "月最小值", round(avg(jz),4) as "月平均值", max(jz) as "月最大值"from jjjzwhere dm='660008' and year(date1)='2018'group by month(date1)order by 1;...