目标理解 INNER JOIN 和 LEFT JOIN掌握子查询用法实操示例创建部门表CREATE TABLE department ( id INT AUTO_INCREMENT PRIMARY KEY, dept_name VARCHAR(20), manager VARCHAR(50));INSERT INTO department(dept_name, manager)VALUES ('dev','Jack'), ('ops','Mike'), ('hr','Lily');连接查询（JOIN）SELECT e.name, d.manager, e.salaryFROM employee eLEFT JOIN department d ON e.dept = d.dept_nameWHERE e.salary > 9000;子查询示例SELECT * FROM employeeWHERE salary > ( SELECT AVG(salary) FROM employee);视图与存储过程目标封装常用查询逻辑提升 SQL 复用性实操示例创建视图CREATE VIEW high_salary ASSELECT name, dept, salary FROM employee WHERE salary > 10000;SELECT * FROM high_salary;更新视图数据（会影响原表）UPDATE high_salary SET salary = 15000 WHERE name='Alice';存储过程DELIMITER $$CREATE PROCEDURE raise_salary( IN p_dept VARCHAR(20), IN percent INT)BEGIN UPDATE employee SET salary = salary * (1 + percent/100) WHERE dept = p_dept;END$$DELIMITER ;CALL raise_salary('dev', 10);用户权限与安全目标管理用户权限设置安全策略实操示例创建用户并授权CREATE USER 'appuser'@'%' IDENTIFIED BY 'StrongPass123!';GRANT SELECT, INSERT, UPDATE ON company.* TO 'appuser'@'%';FLUSH PRIVILEGES;查看用户权限SHOW GRANTS FOR 'appuser'@'%';限制 IP 段访问CREATE USER 'devops'@'192.168.%.%' IDENTIFIED BY 'pwd123';撤销权限REVOKE UPDATE ON company.* FROM 'appuser'@'%';