第十二课 连接和高级连接

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