SQL Join3
1. 前言
DROP TABLE IF EXISTS imooc_employee;CREATE TABLE imooc_employee(
id int PRIMARY KEY,
employee_name varchar(),
salary int,
manager_id int);INSERT INTO imooc_employee VALUES(, 'Joe', , );INSERT INTO imooc_employee VALUES(, 'Henry', , );INSERT INTO imooc_employee VALUES(, 'Sam', , NULL);INSERT INTO imooc_employee VALUES(, 'Pedro', , NULL);
2. 自连接
SELECT .employee_nameFROM imooc_employee AS JOIN imooc_employee AS ON .manager_id = .idWHERE .salary > .salary;
+---------------+
| employee_name |
+---------------+
| Joe |
+---------------+