MySQL_连接查询_小结

Sql92 VS sql99

功能

       Sql99支持的较多

可读性

       Sql99实现连接条件和筛选条件的分离，可读性较高

#内连接
SELECT<select_list>
FROM A
INNER JOIN B
ON A.key = B.key

#左外连接
SELECT<select_list>
FROM A
LEFT JOIN B
ON A.key = B.key

#右外连接
SELECT<select_list>
FROM A
RIGHT JOIN B
ON A.key = B.key

#全外连接
SELECT<select_list>
FROM A
FULL JOIN B
ON A.key = B.key