using等价于join操作中的on，例如a和b根据id字段关联，那么以下等价
using(id)
on a.id=b.id
以下2个实例等价：
select a.name,b.age from test as a
join test2 as b
on a.id=b.id
select a.name,b.age from test as a
join test2 as b
using(id)
原文：https://blog.csdn.net/gaozongjian/article/details/79622414