一、创建联结
join：分成inner join left join right join 后面跟着on作为联结条件
select * from products; select * from vendors; select * from products inner join vendors on products.vend_id = vendors.vend_id
其中inner join 是内连接，left左连接，right 右连接
join：分成inner join left join right join 后面跟着on作为联结条件
select * from products; select * from vendors; select * from products inner join vendors on products.vend_id = vendors.vend_id
其中inner join 是内连接，left左连接，right 右连接
原文：https://www.cnblogs.com/slowlyslowly/p/8656489.html