MySQL 创建联结

寤鸿〃

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);

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

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

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

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

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

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;

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;

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