MYSQL字段操作与表关联
本文介绍了MYSQL中如何增加字段、拆分表格的方法，并详细解释了几种表关联查询的使用方式，包括内连接、左连接及交叉连接等，为数据库管理和查询提供了实用技巧。
MYSQL 增加字段
alter xdtabl add name char;
mysql 拆分表格
create Table s3 select * from s1 order by id limit 150,100
inner join：
select * from A inner join B on A.name = B.name;
mysql> select * from A left join B on A.name = B.name;
select * from A left join B on A.name=B.name where A.id is null or B.id is null;
mysql> select * from A left join B on A.name=B.name where A.id is not null and B.id is not null;
mysql> select * from A left join B on A.name=B.name where A.id is not null and B.id is not null;
mysql> select * from A cross join B;
select * from A left join B on B.name = A.name
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