Mysql统计名字相同的用户实现流程
1. 创建数据库和数据表
首先,我们需要创建一个数据库和数据表来存储用户信息。
CREATE DATABASE userdb;
USE userdb;
CREATE TABLE users (
id INT AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(255),
age INT,
address VARCHAR(255)
);
2. 插入测试数据
为了演示统计名字相同的用户,我们需要插入一些测试数据。
INSERT INTO users (name, age, address) VALUES ('John', 25, '123 Main St');
INSERT INTO users (name, age, address) VALUES ('John', 30, '456 Elm St');
INSERT INTO users (name, age, address) VALUES ('Emily', 28, '789 Oak St');
INSERT INTO users (name, age, address) VALUES ('Emily', 32, '321 Pine St');
INSERT INTO users (name, age, address) VALUES ('Michael', 35, '555 Maple St');
3. 统计名字相同的用户
我们使用GROUP BY
和COUNT()
函数来统计名字相同的用户,并按照名字进行分组。
SELECT name, COUNT(*) AS count FROM users GROUP BY name;
4. 整个过程的代码实现
下面是整个过程的代码实现,包括创建数据库和数据表、插入测试数据以及统计名字相同的用户。
-- 创建数据库和数据表
CREATE DATABASE userdb;
USE userdb;
CREATE TABLE users (
id INT AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(255),
age INT,
address VARCHAR(255)
);
-- 插入测试数据
INSERT INTO users (name, age, address) VALUES ('John', 25, '123 Main St');
INSERT INTO users (name, age, address) VALUES ('John', 30, '456 Elm St');
INSERT INTO users (name, age, address) VALUES ('Emily', 28, '789 Oak St');
INSERT INTO users (name, age, address) VALUES ('Emily', 32, '321 Pine St');
INSERT INTO users (name, age, address) VALUES ('Michael', 35, '555 Maple St');
-- 统计名字相同的用户
SELECT name, COUNT(*) AS count FROM users GROUP BY name;
类图
classDiagram
class Database {
+createUserTable()
+insertTestData()
+countSameNameUsers()
}
class Developer {
+teachNewbie()
}
class Newbie {
+learnFrom(Developer)
}
class Main {
+main()
}
Database ..> Developer
Newbie --> Developer
Newbie --> Main
旅行图
journey
title Mysql统计名字相同的用户实现流程
section 创建数据库和数据表
Database->Database:createUserTable()
Database->Database:insertTestData()
section 统计名字相同的用户
Newbie->Developer:learnFrom(Developer)
Developer->Database:countSameNameUsers()
section 示例代码
Main->Database:createUserTable()
Main->Database:insertTestData()
Main->Developer:teachNewbie()
Main->Newbie:learnFrom(Developer)
Main->Database:countSameNameUsers()