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2208/触发器练习题.md
@ -120,78 +120,491 @@ SET MESSAGE_TEXT = '错误消息';
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创建一个触发器 `before_employee_insert`，在插入 `employee` 表数据之前，检查员工的工资是否在其对应职位的 `min_salary` 和 `max_salary` 范围内。如果超出范围，阻止插入并抛出错误。
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```sql
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DELIMITER $$
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DROP TRIGGER IF EXISTS before_employee_insert;
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CREATE TRIGGER before_employee_insert
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BEFORE INSERT ON employee
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FOR EACH ROW
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BEGIN
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IF NEW.salary > (
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SELECT j.max_salary
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FROM job j
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WHERE j.job_id = NEW.job_id
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) OR NEW.salary < (
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SELECT j.min_salary
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FROM job j
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WHERE j.job_id = NEW.job_id
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) THEN
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SIGNAL SQLSTATE '45000'
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SET MESSAGE_TEXT = '工资值错误，不在职务工资范围内';
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END IF;
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END $$
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DELIMITER ;
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INSERT INTO employee
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VALUES(DEFAULT, '雷昊', 0, NOW(), 1, 1);
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```
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#### 练习题 2: 自动更新部门人数
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创建一个触发器 `after_employee_insert`，在插入 `employee` 表数据之后，自动更新 `department` 表中的部门人数（假设 `department` 表新增一个字段 `employee_count`）。
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```sql
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ALTER TABLE department ADD employee_count INT UNSIGNED;
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DELIMITER $$
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DROP TRIGGER IF EXISTS after_employee_insert;
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CREATE TRIGGER after_employee_insert
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AFTER INSERT ON employee
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FOR EACH ROW
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BEGIN
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UPDATE department d
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SET d.employee_count = (
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SELECT COUNT(*)
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FROM employee e
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WHERE e.dept_id = d.dept_id
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);
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END $$
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DELIMITER ;
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INSERT INTO employee
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VALUES(DEFAULT, '雷昊', 60000.00, NOW(), 1, 1);
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```
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#### 练习题 3: 工资变更日志
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创建一个触发器 `after_employee_update`，在更新 `employee` 表的 `salary` 字段后，将变更记录插入到一个新的日志表 `salary_log` 中，记录员工 ID、旧工资、新工资和变更时间。
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```sql
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DROP TABLE IF EXISTS salary_log;
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CREATE TABLE salary_log(
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emp_id INT,
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old_salary DECIMAL(10, 2),
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new_slaray DECIMAL(10, 2),
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update_date DATE
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);
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DELIMITER $$
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DROP TRIGGER IF EXISTS after_employee_update;
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CREATE TRIGGER after_employee_update
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BEFORE UPDATE ON employee
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FOR EACH ROW
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BEGIN
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IF NEW.salary <> OLD.salary THEN
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INSERT INTO salary_log()
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VALUES(NEW.emp_id, OLD.salary, NEW.salary, NOW());
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END IF;
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END $$
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DELIMITER ;
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UPDATE employee e
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SET e.salary = 10
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WHERE e.emp_id = 1;
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```
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#### 练习题 4: 删除员工时备份数据
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创建一个触发器 `before_employee_delete`，在删除 `employee` 表数据之前，将被删除的员工数据插入到一个备份表 `employee_backup` 中。
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```sql
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CREATE TABLE employee_backup AS
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SELECT *
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FROM employee
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WHERE 0;
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DELIMITER $$
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DROP TRIGGER IF EXISTS before_employee_delete;
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CREATE TRIGGER before_employee_delete
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BEFORE DELETE ON employee
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FOR EACH ROW
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BEGIN
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INSERT INTO employee_backup()
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VALUES(OLD.emp_id, OLD.emp_name, OLD.salary, OLD.hire_date, OLD.dept_id, OLD.job_id);
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END $$
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DELIMITER ;
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DELETE FROM employee
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WHERE emp_id = 20;
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```
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#### 练习题 5: 自动设置默认职位
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创建一个触发器 `before_employee_insert`，在插入 `employee` 表数据时，如果未指定 `job_id`，则自动将其设置为 `job` 表中的默认职位（假设默认职位的 `job_id` 为 1）。
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```sql
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DELIMITER $$
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DROP TRIGGER IF EXISTS before_employee_insert;
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CREATE TRIGGER before_employee_insert
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BEFORE INSERT ON employee
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FOR EACH ROW
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BEGIN
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IF NEW.job_id IS NULL THEN
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SET NEW.job_id = 1;
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END IF;
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END $$
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DELIMITER ;
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INSERT INTO employee
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VALUES(DEFAULT, '雷昊', 60000.00, NOW(), 1, NULL);
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```
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#### 练习题 6: 防止修改入职日期
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创建一个触发器 `before_employee_update`，在更新 `employee` 表数据时，防止修改 `hire_date` 字段。如果尝试修改，抛出错误。
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```sql
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DELIMITER $$
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DROP TRIGGER IF EXISTS before_employee_update;
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CREATE TRIGGER before_employee_update
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BEFORE UPDATE ON employee
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FOR EACH ROW
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BEGIN
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IF NEW.hire_date <> OLD.hire_date THEN
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SIGNAL SQLSTATE '45000'
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SET MESSAGE_TEXT='不允许修改用户的入职时间';
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END IF;
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END $$
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DELIMITER ;
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UPDATE employee e
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SET e.hire_date = '2025-3-20'
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WHERE e.emp_id = 1;
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```
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#### 练习题 7: 自动计算工龄
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创建一个触发器 `before_employee_insert`，在插入 `employee` 表数据时，自动计算员工的工龄（以年为单位），并将其存储到一个新字段 `years_of_service` 中。
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```sql
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ALTER TABLE employee ADD years_of_service INT;
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DELIMITER $$
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DROP TRIGGER IF EXISTS before_employee_insert;
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CREATE TRIGGER before_employee_insert
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BEFORE INSERT ON employee
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FOR EACH ROW
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BEGIN
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SET NEW.years_of_service = TIMESTAMPDIFF(YEAR,NEW.hire_date,NOW());
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END $$
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DELIMITER ;
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SELECT TIMESTAMPDIFF(YEAR,e.hire_date,NOW())
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FROM employee e;
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INSERT INTO employee
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VALUES(DEFAULT, '雷昊', 60000.00, '2022-12-31', 1, 1, NULL);
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```
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#### 练习题 8: 防止删除部门
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创建一个触发器 `before_department_delete`，在删除 `department` 表数据之前，检查该部门是否还有员工。如果有员工，阻止删除并抛出错误。
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```sql
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DELIMITER $$
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DROP TRIGGER IF EXISTS before_department_delete;
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CREATE TRIGGER before_department_delete
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BEFORE DELETE ON department
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FOR EACH ROW
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BEGIN
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IF (SELECT COUNT(*) FROM employee e WHERE e.dept_id = OLD.dept_id) > 0 THEN
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SIGNAL SQLSTATE '45000'
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SET MESSAGE_TEXT = '该部门有员工无法删除';
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END IF;
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END $$
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DELIMITER ;
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DELETE FROM department
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WHERE dept_id = 1;
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```
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#### 练习题 9: 自动更新职位工资范围
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创建一个触发器 `after_job_update`，在更新 `job` 表的 `min_salary` 或 `max_salary` 字段后，自动调整 `employee` 表中相关员工的工资，使其符合新的工资范围。
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```sql
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DELIMITER $$
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DROP TRIGGER IF EXISTS after_job_update;
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CREATE TRIGGER after_job_update
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AFTER UPDATE ON job
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FOR EACH ROW
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BEGIN
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UPDATE employee
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SET salary = IF(salary > NEW.max_salary, NEW.max_salary, IF(salary < NEW.min_salary, min_salary, salary))
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WHERE job_id = NEW.job_id;
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END $$
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DELIMITER ;
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```
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#### 练习题 10: 记录部门变更
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创建一个触发器 `after_employee_update`，在更新 `employee` 表的 `dept_id` 字段后，将变更记录插入到一个新的日志表 `department_change_log` 中，记录员工 ID、旧部门 ID、新部门 ID 和变更时间。
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```sql
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CREATE TABLE department_change_log(
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emp_id INT,
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old_dept_id INT,
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new_dept_id INT,
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update_date DATE
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);
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DELIMITER $$
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DROP TRIGGER IF EXISTS after_employee_update;
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CREATE TRIGGER after_employee_update
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AFTER UPDATE ON employee
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FOR EACH ROW
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BEGIN
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IF NEW.dept_id <> OLD.dept_id THEN
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INSERT INTO department_change_log()
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VALUES(NEW.emp_id, OLD.dept_id, NEW.dept_id, NOW());
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END IF;
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END $$
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DELIMITER ;
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```
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#### 练习题 11: 防止插入重复职位
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创建一个触发器 `before_job_insert`，在插入 `job` 表数据之前，检查职位名称是否已存在。如果存在，阻止插入并抛出错误。
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```sql
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DELIMITER $$
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DROP TRIGGER IF EXISTS before_job_insert;
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CREATE TRIGGER before_job_insert
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BEFORE INSERT ON job
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FOR EACH ROW
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BEGIN
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IF (SELECT COUNT(*) FROM job WHERE job_id = NEW.job_id) = 1 THEN
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SIGNAL SQLSTATE '45000'
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SET MESSAGE_TEXT = '职位名称已存在';
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END IF;
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END $$
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DELIMITER ;
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```
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#### 练习题 12: 自动更新员工总数
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创建一个触发器 `after_employee_insert`，在插入 `employee` 表数据之后，自动更新一个统计表 `employee_statistics` 中的员工总数。
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```sql
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CREATE TABLE employee_statistics(
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marking VARCHAR(20),
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num INT
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);
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INSERT INTO employee_statistics()
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VALUES('count', 0);
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DELIMITER $$
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DROP TRIGGER IF EXISTS after_employee_insert;
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CREATE TRIGGER after_employee_insert
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AFTER INSERT ON employee
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FOR EACH ROW
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BEGIN
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UPDATE employee_statistics
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SET num = (SELECT COUNT(*) FROM employee)
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WHERE marking = 'count';
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END $$
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DELIMITER ;
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```
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#### 练习题 13: 防止修改部门所在地
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创建一个触发器 `before_department_update`，在更新 `department` 表数据时，防止修改 `location` 字段。如果尝试修改，抛出错误。
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```sql
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DELIMITER $$
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DROP TRIGGER IF EXISTS before_department_update;
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CREATE TRIGGER before_department_update
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BEFORE UPDATE ON department
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FOR EACH ROW
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BEGIN
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IF NEW.location <> OLD.location THEN
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SIGNAL SQLSTATE '45000'
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SET MESSAGE_TEXT = '无法更新部分的位置';
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END IF;
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END $$
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DELIMITER ;
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```
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#### 练习题 14: 自动调整工资
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创建一个触发器 `before_employee_insert`，在插入 `employee` 表数据时，如果工资低于职位的最低工资，则自动将其调整为最低工资。
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```sql
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DELIMITER $$
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DROP TRIGGER IF EXISTS before_employee_insert;
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CREATE TRIGGER before_employee_insert
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BEFORE INSERT ON employee
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FOR EACH ROW
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BEGIN
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IF NEW.salary < (SELECT min_salary FROM job WHERE job_id = NEW.job_id ) THEN
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SET NEW.salary = min_salary;
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END IF;
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END $$
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DELIMITER ;
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```
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#### 练习题 15: 记录职位变更
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创建一个触发器 `after_employee_update`，在更新 `employee` 表的 `job_id` 字段后，将变更记录插入到一个新的日志表 `job_change_log` 中，记录员工 ID、旧职位 ID、新职位 ID 和变更时间。
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```sql
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CREATE TABLE job_change_log(
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emp_id INT,
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old_job_id INT,
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new_job_id INT,
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update_date DATE
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);
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DELIMITER $$
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DROP TRIGGER IF EXISTS after_employee_update;
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CREATE TRIGGER after_employee_update
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AFTER UPDATE ON employee
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FOR EACH ROW
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BEGIN
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IF NEW.job_id <> OLD.job_id THEN
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INSERT INTO job_change_log()
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VALUES(NEW.emp_id, OLD.job_id, NEW.job_id, NOW());
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END IF;
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END $$
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DELIMITER ;
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```
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#### 练习题 16: 防止删除职位
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创建一个触发器 `before_job_delete`，在删除 `job` 表数据之前，检查该职位是否还有员工。如果有员工，阻止删除并抛出错误。
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```sql
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DELIMITER $$
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DROP TRIGGER IF EXISTS before_job_delete;
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CREATE TRIGGER before_job_delete
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BEFORE DELETE ON job
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FOR EACH ROW
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BEGIN
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IF (SELECT COUNT(*) FROM employee WHERE job_id = OLD.job_id) > 0 THEN
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SIGNAL SQLSTATE '45000'
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SET MESSAGE_TEXT = '该职位还有员工';
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END IF;
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END $$
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DELIMITER ;
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```
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#### 练习题 17: 自动更新部门平均工资
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|
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创建一个触发器 `after_employee_insert`，在插入 `employee` 表数据之后，自动更新 `department` 表中的部门平均工资（假设 `department` 表新增一个字段 `avg_salary`）。
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|
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```sql
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DELIMITER $$
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DROP TRIGGER IF EXISTS after_employee_insert;
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CREATE TRIGGER after_employee_insert
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AFTER INSERT ON employee
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FOR EACH ROW
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BEGIN
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UPDATE department d
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SET d.avg_salary = (SELECT AVG(e.salary) FROM employee e WHERE d.dept_id = e.dept_id)
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WHERE NEW.dept_id = d.dept_id;
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END $$
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DELIMITER ;
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```
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#### 练习题 18: 防止插入未来入职日期
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|
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创建一个触发器 `before_employee_insert`，在插入 `employee` 表数据时，检查 `hire_date` 是否晚于当前日期。如果是，阻止插入并抛出错误。
|
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|
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```sql
|
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DELIMITER $$
|
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DROP TRIGGER IF EXISTS before_employee_insert;
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CREATE TRIGGER before_employee_insert
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BEFORE INSERT ON employee
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FOR EACH ROW
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BEGIN
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IF NEW.hire_date < CURDATE() THEN
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SIGNAL SQLSTATE '45000'
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SET MESSAGE_TEXT = '入职日期不得晚于当前日期';
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END IF;
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|
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END $$
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DELIMITER ;
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```
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#### 练习题 19: 自动生成员工编号
|
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|
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创建一个触发器 `before_employee_insert`，在插入 `employee` 表数据时，自动生成一个唯一的员工编号（格式为 `EMP-年份-序号`，例如 `EMP-2023-001`），并将其存储到一个新字段 `emp_code` 中。
|
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|
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```sql
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ALTER TABLE employee ADD emp_code VARCHAR(30);
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DELIMITER $$
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DROP TRIGGER IF EXISTS before_employee_insert;
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CREATE TRIGGER before_employee_insert
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BEFORE INSERT ON employee
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FOR EACH ROW
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BEGIN
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SET NEW.emp_code = CONCAT('EMP-',YEAR(NOW()),'-', (LAST_INSERT_ID()+1));
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END $$
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DELIMITER ;
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INSERT INTO employee
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VALUES(DEFAULT, '雷昊', 0, NOW(), 1, 1, NULL, NULL);
|
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```
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#### 练习题 20: 记录员工离职
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|
||||
创建一个触发器 `after_employee_delete`，在删除 `employee` 表数据之后，将被删除的员工信息插入到一个离职记录表 `employee_exit_log` 中，记录员工 ID、姓名、离职时间和原因（假设原因由用户输入）。
|
||||
创建一个触发器 `after_employee_delete`，在删除 `employee` 表数据之后，将被删除的员工信息插入到一个离职记录表 `employee_exit_log` 中，记录员工 ID、姓名、离职时间和原因（假设原因由用户输入）。
|
||||
|
||||
```sql
|
||||
CREATE TABLE employee_exit_log(
|
||||
emp_id INT,
|
||||
emp_name VARCHAR(20),
|
||||
quit_date DATE,
|
||||
quit_reason VARCHAR(50)
|
||||
);
|
||||
|
||||
DELIMITER $$
|
||||
DROP TRIGGER IF EXISTS after_employee_delete;
|
||||
CREATE TRIGGER after_employee_delete
|
||||
AFTER DELETE ON employee
|
||||
FOR EACH ROW
|
||||
BEGIN
|
||||
INSERT INTO employee_exit_log()
|
||||
VALUES(OLD.emp_id, OLD.emp_name, NOW(), NULL);
|
||||
END $$
|
||||
DELIMITER ;
|
||||
```
|
||||
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user