mysql 表连接

1、三个表连接SELECT * FROM stock320151203 as a , stock320151202 as b , stock320151201 as c WHERE a.id=b.id and a.id=c.id;

两个表连接：SELECT * FROM stock320151203 as a , stock320151202 as b WHERE a.id=b.id ;

等同于：

SELECT * FROM stock320151203 as a LEFT JOIN stock320151202 as b on a.id=b.id ;

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Left Join 语法：

select   *   from
table1   left   join   table2   on   条件1   
left   join   table3   on   条件2   
left   join   table4   on   条件3  
where   条件4

 

注1：union用法如下。union是上下添加，left join是左右表连接

SELECT * FROM stock320151203 UNION SELECT * FROM stock320151202 ; 

注2：笛卡尔积

SELECT * FROM stock320151203 join  stock320151202 ;【每一行都交叉想乘了，相当于十字相乘】

 

2、满足两个表的mysql语法

SELECT * FROM stock320151202 where id =any(SELECT id FROM stock320151203 where zhangfu > 9.8) and zhangfu >9.8;

3、select语句新建一个表

 CREATE TABLE newtest SELECT id , name ,zhangfu ,open_price,last_closed_price,now_price,high_price,1.5*deal_gupiao,deal_jine,riqi,time FROM stock320151203  ;

 

四、授权任何地方都可以访问

grant all privileges on mindo.* to root@"%" identified by 'sf2014' with grant option;