# jdbc

**Repository Path**: hrbu-2022/jdbc

## Basic Information

- **Project Name**: jdbc
- **Description**: 练习jdbc项目
- **Primary Language**: Unknown
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 1
- **Forks**: 0
- **Created**: 2024-11-08
- **Last Updated**: 2025-11-09

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# 准备驱动

到maven的网站搜素 [https://mvnrepository.com/](https://mvnrepository.com/)





[https://mvnrepository.com/artifact/com.mysql/mysql-connector-j/8.3.0](https://mvnrepository.com/artifact/com.mysql/mysql-connector-j/8.3.0)

![image-20241108085321274](imgs/image-20241108085321274.png)

# 添加到IDEA项目中，并作为一个库存在（类似于JDK）

- 新建目录libs

  ![image-20241108085610029](imgs/image-20241108085610029.png)

- 复制jar包到 libs目录

- 设置为库

![image-20241108085656382](imgs/image-20241108085656382.png)

![image-20241108085718586](imgs/image-20241108085718586.png)

# 编写第一个jdbc程序



```java
package com.neuedu.jdbc;

import java.sql.*;

/**
 * @author 金山
 * 项目：jdbc
 * site: https://blog.fulfill.com.cn
 * 描述  入门
 * @data 2024/11/88:48
 */
public class JDBCTest {


    /**
     * 旧版本  8-
     * // Class.forName("com.mysql.jdbc.Driver");
     * @param args
     */
    public static void main(String[] args) {



        Connection con = null;
        Statement stmt = null;
        ResultSet rs = null;
        try {
            //载入JDBC驱动程序：  //8.0+
            Class.forName("com.mysql.cj.jdbc.Driver");

            //建立数据库连接对象：
            // String url = "http://www.baidu.com:80/search";

            // String url = "jdbc:mysql//localhost:3306/test";
            String url = "jdbc:mysql://127.0.0.1:3306/test";
            String username = "root";
            String password = "root";
            con = DriverManager.getConnection(url,username,password);

            //创建Statement对象
            stmt = con.createStatement();

            /**
             * CRUD  增删改查
             * query   :  select
             * update   : insert  update   delete
             */
            String sql = " select count(1) c from emp ";
            rs = stmt.executeQuery(sql);


            //解析结果集
           if(rs.next()){  //进入到 if 中说明有数据

                //rs 现在指向的是数据 行
               // int count = rs.getInt(1);
               int count = rs.getInt("c");


               System.out.println("count = " + count);
           }


        } catch (ClassNotFoundException | SQLException e) {
            throw new RuntimeException(e);
        }finally {
            //关闭资源
            if(rs != null){
                try {
                    rs.close();
                } catch (SQLException e) {
                    throw new RuntimeException(e);
                }
            }

            if(stmt != null){
                try {
                    stmt.close();
                } catch (SQLException e) {
                    throw new RuntimeException(e);
                }
            }
            if(con != null){
                try {
                    con.close();
                } catch (SQLException e) {
                    throw new RuntimeException(e);
                }
            }

        }

    }

}

```



# 事务操作

```sql
-- 创建账户表
CREATE  TABLE account(
   id INT AUTO_INCREMENT PRIMARY KEY,
   NAME VARCHAR(1000) NOT NULL,
   amount DECIMAL(8,2)

);


-- 准备数据
INSERT INTO account(NAME,amount)
VALUES
('张三',2000),
('李四',2000);


SELECT * FROM account;


-- 转账 张三给李四转账 500



-- 给张三 减去 500
UPDATE  account SET amount = amount - 500 WHERE id = 1;


-- 李四 加上 500
UPDATE  account SET amount = amount + 500 WHERE id = 2;







```

# 单元测试

使用JUnit

- 下载 https://mvnrepository.com/artifact/junit/junit/4.13.2
- https://repo1.maven.org/maven2/junit/junit/4.13.2/junit-4.13.2.jar

赋值  jar 到  libs中， 使用 Libs



![image-20241108134210217](imgs/image-20241108134210217.png)