srkp.net
当前位置:首页 >> mysql 联合 >>

mysql 联合

SELECT A.ID, A.NUMBER, A.PRICE, A.ORDER_TIME, B.USER_ID, B.STARTIME, B.STOPTIME, C.CHANNEL_PAY, D.COMPANY FROM D表 D LEFT JOIN A表 A ON A.COMPANY_ID = D.UID LEFT JOIN B表 B ON B.COMPANY_ID = D.UID LEFT JOIN C表 C ON C.COMPANY_I...

可以的,你可以随便链接一个数据库 然后,sql语句为 select * from db1.table1 left join db2.table2 on db1.table1.id = db2.table2.id 只要用数据库名加上"."就能调用相应数据库的数据表了. 数据库名.表名

三表联查 只要找出关联的字段关系来联查就行了1,,INNER JOIN ON 2, RIGHT JOIN ON 3 LEFT JOIN ON 4,JOIN ON 差不多就着几个

一使用SELECT子句进行多表查询 SELECT 字段名 FROM 表1,表2 … WHERE 表1.字段 = 表2.字段 AND 其它查询条件 SELECT a.id,a.name,a.address,a.date,b.math,b.english,b.chinese FROM tb_demo065_tel AS b,tb_demo065 AS a WHERE a.id=b.id 注:在...

SELECT m.user_id, b_total, c_total, d_total FROM a m, (SELECT user_id, COUNT(*) b_total FROM b GROUP BY user_id) n, (SELECT user_id, COUNT(*) c_total FROM c GROUP BY user_id) j, (SELECT user_id, COUNT(*) d_total FROM d GROUP BY...

create table table_name ( userid int not null, goodsid int not null, primary key (userid,goodsid) ) engine=innodb default charset=gbk

Mysql多表联合索引: 1、多表联合索引在查询语句中能加速查询速度。select * from table1,table2 where table1.id = table2.id。 2、多表联合的索引的sql语法,一个user表有4个字段 id name age sex,分别给name age sex建立三个单独的索引,此时...

SELECT shop.id,shop.`name`,card.id as cid,card.sid,card.cname FROM shop , card WHERE shop.id = card.sid 这是一种最直白的方式查询方式,也可以用join

这么写: select uid,name,max(dateline) dateline from a,b where a.uid = b.uid group by uid,name order by max(dateline)

这简答 select 人员,count(1) as 产量 from ( select 人员,产量 from 表1 union all select 人员,产量 from 表2 ) t group by 人员

网站首页 | 网站地图
All rights reserved Powered by www.srkp.net
copyright ©right 2010-2021。
内容来自网络,如有侵犯请联系客服。zhit325@qq.com