sql joins

1. 内连接
   select <字段> from tableA A inner join tableB B on A.key = B.key;
   

2. 左连接
   select <字段> from tableA A left join tableB B on A.key = B.key;
   

3. 右连接
   select <字段> from tableA A right join tableB B on A.key = B.key;
   

select <字段> from tableA A left join tableB B on A.key = B.key where B.key is null;

5. select <字段> from tableA A right join tableB B on A.key = B.key where A.key is null;

6. 全连接
select <字段> from tableA A full out join tableB B on A.key = B.key ;

7.
select <字段> from tableA A full out join tableB B on A.key = B.key where A.key is null or B.key is null;

										**帅气的远远啊**

来源：CSDN

作者：yuanyuan啊

链接：https://blog.csdn.net/qq_41585840/article/details/104079590