史上最全 MySQL JOIN 查询

建表
在这里呢我们先来建立两张有外键关联的张表。

	CREATE DATABASE db0206;
	USE db0206;
	
	CREATE TABLE `db0206`.`tbl_dept`(  
	  `id` INT(11) NOT NULL AUTO_INCREMENT,
	  `deptName` VARCHAR(30),
	  `locAdd` VARCHAR(40),
	  PRIMARY KEY (`id`)
	) ENGINE=INNODB CHARSET=utf8;
	
	CREATE TABLE `db0206`.`tbl_emp`(  
	  `id` INT(11) NOT NULL AUTO_INCREMENT,
	  `name` VARCHAR(20),
	  `deptId` INT(11),
	  PRIMARY KEY (`id`),
	  FOREIGN KEY (`deptId`) REFERENCES `db0206`.`tb_dept`(`id`)
	) ENGINE=INNODB CHARSET=utf8;
	/*插入数据*/
	INSERT INTO tbl_dept(deptName,locAdd) VALUES('RD',11);
	INSERT INTO tbl_dept(deptName,locAdd) VALUES('HR',12);
	INSERT INTO tbl_dept(deptName,locAdd) VALUES('MK',13);
	INSERT INTO tbl_dept(deptName,locAdd) VALUES('MIS',14);
	INSERT INTO tbl_dept(deptName,locAdd) VALUES('FD',15);
	
	INSERT INTO tbl_emp(NAME,deptId) VALUES('z3',1);
	INSERT INTO tbl_emp(NAME,deptId) VALUES('z4',1);
	INSERT INTO tbl_emp(NAME,deptId) VALUES('z5',1);
	
	INSERT INTO tbl_emp(NAME,deptId) VALUES('w5',2);
	INSERT INTO tbl_emp(NAME,deptId) VALUES('w6',2);
	
	INSERT INTO tbl_emp(NAME,deptId) VALUES('s7',3);
	
	INSERT INTO tbl_emp(NAME,deptId) VALUES('s8',4);

内连接
内连接文氏图

执行的sql语句

select * from tbl_dept a inner join tbl_emp b on a.id=b.deptId;

查询结果

左外连接
左外连接文氏图

执行的sql语句

select * from tbl_dept a left join tbl_emp b on a.id=b.deptId;

右外连接
右外连接文氏图

执行的sql语句

	select * from tbl_dept a right join tbl_emp b on a.id=b.deptId;

左连接
左连接文氏图

执行的sql语句

select * from tbl_dept a left join tbl_emp b on a.id=b.deptId where b.deptId is null;

查询结果

右连接
右连接文氏图

执行的sql语句

select * from tbl_dept a right join tbl_emp b on a.id=b.deptId where a.id is null;

全连接
全连接文氏图

执行的sql语句

select * from tbl_dept a right join tbl_emp b on a.id=b.deptId 
union 
select * from tbl_dept a left join tbl_emp b on a.id=b.deptId;

查询结果

全连接
两张表中都没有出现的数据集

执行的sql语句

select * from tbl_dept a right join tbl_emp b on a.id=b.deptId where a.id is null 
union 
select * from tbl_dept a left join tbl_emp b on a.id=b.deptId where b.deptId is null;

查询结果