01.JDBC

0、添加依赖

1、添加依赖

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.47</version>
    <scope>runtime</scope>
</dependency>

2、初始化数据库

create database db1 charset utf8;
use db1;

CREATE TABLE students (
  id BIGINT AUTO_INCREMENT NOT NULL,
  name VARCHAR(50) NOT NULL,
  gender TINYINT(1) NOT NULL,
  grade INT NOT NULL,
  score INT NOT NULL,
  PRIMARY KEY(id)
) Engine=INNODB DEFAULT CHARSET=UTF8;

-- 插入初始数据:
INSERT INTO students (name, gender, grade, score) VALUES ('小明', 1, 1, 88);
INSERT INTO students (name, gender, grade, score) VALUES ('小红', 1, 1, 95);

select * from students;

1、增改删

package org.example;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class JDBCDemo {

    public static void main(String[] args) throws Exception {
        //1. 注册驱动
        Class.forName("com.mysql.jdbc.Driver");
        //2. 获取连接
        String url = "jdbc:mysql://127.0.0.1:3306/db1?useSSL=false";
        String username = "root";
        String password = "123456";
        Connection conn = DriverManager.getConnection(url, username, password);

        //3.1 增
         String sql = "INSERT INTO students (name, gender, grade, score) VALUES ('zhangsan', 1, 1, 88)";
        //3.2 改
        // String sql = "UPDATE students SET score = 100 WHERE name = 'zhangsan'";
        //3.3 删
        // String sql = "DELETE FROM students Where name = 'zhangsan'";

        //4. 获取statement对象
        Statement stmt = conn.createStatement();
        //5. 执行sql
        stmt.executeUpdate(sql);

        //7. 释放资源
        stmt.close();
        conn.close();
    }
}

2、查

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class JDBCDemo {

    public static void main(String[] args) throws Exception {
        //1. 注册驱动
        Class.forName("com.mysql.jdbc.Driver");
        //2. 获取连接
        String url = "jdbc:mysql://127.0.0.1:3306/db1?useSSL=false";
        String username = "root";
        String password = "123456";
        Connection conn = DriverManager.getConnection(url, username, password);
        //3. 查询数据
        //3. 定义sql
        String sql = "select * from students";
        //4. 获取statement对象
        Statement stmt = conn.createStatement();
        //5. 执行sql
        ResultSet rs = stmt.executeQuery(sql);
        // 6.1 光标向下移动一行，并且判断当前行是否有数据
        while (rs.next()){
            //6.2 获取数据  getXxx()
            int id = rs.getInt("id");
            String name = rs.getString("name");

            System.out.println(id);
            System.out.println(name);

            System.out.println("--------------");
        }

        //7. 释放资源
        rs.close();
        stmt.close();
        conn.close();
    }
}