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mysql数据的增删改案例
直接po截图和代码
#mysql数据的增删改案例
USE myemployees;
#1.运行以下脚本创建表my_employees
CREATE TABLE my_employees(
Id INT(10),
First_name VARCHAR(10),
Last_name VARCHAR(10),
Userid VARCHAR(10),
Salary DOUBLE(10,2)
);
#
CREATE TABLE users(
id INT,
userid VARCHAR(10),
department_id INT
);
#2.显示表my_employees的结构
DESC my_employees;
#3.向my_employees表中插入下列数据
/*
ID FIRST_NAME LAST_NAME USERID SALARY
1 patel Ralph Rpatel 895
2 Dancs Betty Bdancs 860
3 Biri Ben Bbiri 1100
4 Newman Chad Cnewman 750
5 Ropeburn Audrey Aropebur 1550
*/
#方式一
INSERT INTO my_employees(id, FIRST_NAME, LAST_NAME, USERID, SALARY)
VALUES(1, 'patel', 'Ralph', 'Rpatel', 895),
(2, 'Dancs', 'Betty', 'Bdancs', 860),
(3, 'Biri', 'Ben', 'Bbiri', 1100),
(4, 'Newman', 'Chad', 'Cnewman', 750),
(5, 'Ropeburn', 'Audrey', 'Aropebur', 1550);
#
SELECT * FROM my_employees;
#
DELETE FROM my_employees;
#表名后面省略字段
INSERT INTO my_employees
VALUES(1, 'patel', 'Ralph', 'Rpatel', 895),
(2, 'Dancs', 'Betty', 'Bdancs', 860),
(3, 'Biri', 'Ben', 'Bbiri', 1100),
(4, 'Newman', 'Chad', 'Cnewman', 750),
(5, 'Ropeburn', 'Audrey', 'Aropebur', 1550);
#方式二(用到了子查询和UNION联合查询)
INSERT INTO my_employees
SELECT 1, 'patel', 'Ralph', 'Rpatel', 895 UNION
SELECT 2, 'Dancs', 'Betty', 'Bdancs', 860 UNION
SELECT 3, 'Biri', 'Ben', 'Bbiri', 1100 UNION
SELECT 4, 'Newman', 'Chad', 'Cnewman', 750 UNION
SELECT 5, 'Ropeburn', 'Audrey', 'Aropebur', 1550;
#4.向users表中插入数据
/*
1 Rpatel 10
2 Bdancs 10
3 Bbiri 20
4 Cnewman 30
5 Aropebur 40
*/
#
INSERT INTO users
VALUES(1, 'Rpatel', 10),
(2, 'Bdancs', 10),
(3, 'Bbiri', 20),
(4, 'Cnewman', 30),
(5, 'Aropebur', 40);
#
SELECT * FROM users;
#
#5.将3号员工的last_name修改为“drelxer”
UPDATE my_employees SET Last_name = 'drelxer' WHERE id = 3;
#6.将所有工资少于900的员工的工资修改为1000
UPDATE my_employees SET Salary = 1000 WHERE Salary < 900;
#7.将userid 为Bbiri的user表和my_employees表的记录全部删除
#级联删除/修改多表
DELETE u, m FROM users u INNER JOIN my_employees m
ON u.userid = m.`Userid`
WHERE u.`Userid` = 'Bbiri';
#8.删除所有数据
DELETE FROM my_employees;
DELETE FROM users;
#9.检查所作的修正
SELECT * FROM my_employees;
SELECT * FROM users;
#10.清空表my_employees
TRUNCATE TABLE my_employees;