java对mysql数据库的增删改查代码

Posted 2020-09-11

首先是用java在mysql中增加数据

import java.sql.*

public class jdbc{

    public static void main (String[] args){
        String driver = "org.git.mm.mysql.Driver";
        String url = ‘jdbc:mysql://localhost:3306/my‘;
        String username = "root";
        String password = "123456";
        String sql = "insert into users (username,password) values(?,?)";

        try{
            Class.forName(driver);
            Connection conn = DriverManager.getConnection(url,username,password);
            PreparedStatement ps = conn.prepareStatement(sql);
            ps.setString(1,"bobuke");
            ps.setString(2,"123456");
            ps.executeUpdate();

            ps.close();
            ps.close();

        } catch (ClassNotFoundException e){
            e.printStackTrace();
        } catch (SQLException e){
            e.printStackTrace();
        }
    }
}      

 

下面是在数据库中查找数据

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Arrays;

public class Demo {

    static String selectsql = null; 
    static ResultSet retsult = null;

    public static final String url = "jdbc:mysql://127.0.0.1/test";
    public static final String name = "com.mysql.jdbc.Driver";
    public static final String user = "root";
    public static final String password = "123456";

    public static Connection conn = null;
    public static PreparedStatement pst = null;    

    public static void main(String[] args) {
        int paraCount = 5; //读取参数数量
        selectsql = "select * from testpass";//SQL语句    

        try {
            Class.forName(name);//指定连接类型
            conn = DriverManager.getConnection(url, user, password);//获取连接
            pst = conn.prepareStatement(selectsql);//准备执行语句
        } catch (Exception e) {
            e.printStackTrace();
        }    

        String [] paras = new String [paraCount];
        try {
            retsult = pst.executeQuery();//执行语句，得到结果集

            while (retsult.next()) {
                for(int i = 0;i<paraCount;i++){
                    paras[i] = retsult.getString(i+2);
                }
                System.out.println(Arrays.toString(paras)); //显示数据

            }

            retsult.close();
            conn.close();//关闭连接
            pst.close();
        } catch (SQLException e) {
             e.printStackTrace();    
        }
    }
}

public class Demo {        //这是对上面的代码进行改进

    public static final String url = "jdbc:mysql://127.0.0.1/test";
    public static final String driver = "com.mysql.jdbc.Driver";
    public static final String user = "root";
    public static final String password = "123456";
  

    public static void main(String[] args) {
        int paraCount = 5; //读取参数数量
        String selectsql = "select * from testpass";//SQL语句    

        try {
            Class.forName(driver);//指定连接类型
            Connection conn = DriverManager.getConnection(url, user, password);//获取连接
            PreparedStatement pst = conn.prepareStatement(selectsql);//准备执行语句
        } catch (Exception e) {
            e.printStackTrace();
        }    

        String [] paras = new String [paraCount];
        try {
            ResultSet retsult = pst.executeQuery();//执行语句，得到结果集

            while (retsult.next()) {
                for(int i = 0;i<paraCount;i++){
                    paras[i] = retsult.getString(i+2); //+2表示留出空格
                }
                System.out.println(Arrays.toString(paras)); //显示数据
            }

            retsult.close();
            conn.close();//关闭连接
            pst.close();
        } catch (SQLException e) {
             e.printStackTrace();    
        }
    }
}

while(result.next())      //上面的while循环部分也可以按照这样的形式来写
        {  
            System.out.print(result.getString("id"));//输出对应表内容，“表的列名”  
            System.out.print("       "+result.getString("name"));  
            System.out.println("       "+result.getString("age"));  
        }