扫码加入数据分析学习群

多表查询中：

>>where的等值联结和内联结一样；子查询也可以等效；on建立联结关系，where筛选

内联结：select * from A inner join B on A.Key = B.Key;

左联结：select * from A left join B on A.Key = B.Key;

右联结：select * from A right join B on A.Key = B.Key;

等值联结：select A_name,B_name,B_mobile from A, B where A.A_id = B.B_id

自联结：select p1.user_id, p1.user_name from usertable as p1, usertable as p2 where p1.user_id = p2.user_id and p2.user_id = '10086';

叉联结：卡迪尔积，没有建立联结关系的表，行数为两表行数相乘

mysql 不支持 full join