jdbc

JDBC理解学习与实现

java database connectivity

1 java连接数据库

JDBC（Java Database Connectivity）是Java提供的用于连接和操作关系数据库的API。JDBC使得Java程序可以与各种数据库系统（如MySQL、Oracle、SQL Server等）进行交互，从而实现数据的存储、查询、更新和删除操作。

2、jdbc连接的api

DriverManager
Connection

sql注入攻击

是指在使用statement接口的时候，sql骚操作获取全部信息；

preparedStatement预防sql攻击

package jdbc_advance;

import org.junit.Test;

import java.sql.*;

public class Prepared_demo1 {
    @Test
    public void testQuerySingleRomAndCol() throws Exception {
        //注册驱动

        Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/atguigu?useSSL=false&serverTimezone=UTC","root","fanTC357");
        PreparedStatement preparedStatement = connection.prepareStatement("select COUNT(*) as count from t_emp");
        ResultSet resultSet = preparedStatement.executeQuery();
        while (resultSet.next()) {
        int count=resultSet.getInt("count");
        System.out.println(count);
        }
        resultSet.close();
        preparedStatement.close();
        connection.close();
    }
}

3、jdbc连接流程实例

package com.atguigu.base;

import java.sql.*;
import java.util.Scanner;

public class jdbc_demo2 {
    public static void main(String[] args) throws Exception{
        //注册驱动
        String url = "jdbc:mysql://localhost:3306/atguigu?useSSL=false&serverTimezone=UTC";
        String user="root";
        String password="******";
        //获得连接
        Connection conn=DriverManager.getConnection(url,user,password);
        //sql语句编写
        Statement stmt=conn.createStatement();

        System.out.println("请输入一个名字");
        Scanner sc=new Scanner(System.in);
        String name=sc.nextLine();

        String sql = "SELECT emp_id,emp_name,emp_salary FROM t_emp WHERE emp_name='"+name+"'";
        ResultSet rs = stmt.executeQuery(sql);

        // 4. 处理结果集
        while (rs.next()) {
            int empId = rs.getInt("emp_id");
            String empName = rs.getString("emp_name");
            double empSalary = rs.getDouble("emp_Salary");
//            int empAge = rs.getInt("emp_Age");不区分大小写
            System.out.println(empId + "\t" + empName + "\t" + empSalary + "\t" );
        }

        // 5. 关闭资源
        rs.close();
        stmt.close();
        conn.close();

    }
}