本文深入解析了SQL中各种连接类型的应用场景与语法，包括左连接、内连接、右连接、全连接及其特定条件下的使用技巧，如处理空值等。
1.
select ... from A left join B on A.key = B.key
2.
select ... from A inner join B on A.key = B.key
3.
select ... from A right join B on A.key = B.key
4.
select ... from A left join B on A.key = B.key
where B.key is NULL
5.
select ... from A right join B on A.key = B.key
where A.key is NULL
6.
select ... from A outer join B on A.key = B.key
7. 这种情况需要注意！
select ... from A outer join B on A.key = B.key where
A.key = NULL or B.key = NULL
扫一扫
172万+
被折叠的 条评论
为什么被折叠?
到【灌水乐园】发言
