mysql 并集、交集、差集

创建两个表

 
CREATE TABLE `object_a` (
 
`id` bigint(20) NOT NULL AUTO_INCREMENT,
 
`oname` varchar(50) DEFAULT NULL,
 
`odesc` varchar(50) DEFAULT NULL,
 
`create_time` datetime DEFAULT NULL,
 
PRIMARY KEY (`id`)
 
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=latin1

添加数据

CREATE TABLE `object_b` (
 
`id` bigint(20) NOT NULL AUTO_INCREMENT,
 
`oname` varchar(50) DEFAULT NULL,
 
`odesc` varchar(50) DEFAULT NULL,
 
`create_time` datetime DEFAULT NULL,
 
PRIMARY KEY (`id`)
 
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=latin1

添加数据

查询并集（union all）

SELECT oname,odesc FROM object_a
 
UNION ALL
 
SELECT oname,odesc FROM object_b

结果如下

查询并集（union）

SELECT oname,odesc FROM object_a
 
UNION
 
SELECT oname,odesc FROM object_b

结果如下

PS：union自带去重

查询交集

SELECT a.oname,a.odesc FROM object_a a INNER JOIN object_b b ON a.oname=b.oname AND a.odesc=b.odesc

等价于

SELECT a.oname,a.odesc FROM object_a a INNER JOIN object_b b USING(oname,odesc)

结果如下

 

PS：别的数据库可以试试这种写法

SELECT oname,odesc FROM object_a
 
INTERSECT
 
SELECT oname,odesc FROM object_b

查询差集

SELECT a.oname, a.odesc
 
FROM
 
object_a a
 
LEFT JOIN object_b b
 
ON a.oname = b.oname
 
AND a.odesc = b.odesc
 
WHERE b.id IS NULL

结果如下

PS：别的数据库可以试试这种写法

SELECT a.oname, a.odesc FROM object_a a
 
MINUS
 
SELECT b.oname, b.odesc FROM object_b b