用java实现对数据库的增删改查

首先引用mysql数据库的jar包文件：右键项目—构建路径—设置构建路径—库—添加外部JAR

我的数据库表及表结构：

DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
  `id` varchar(30) DEFAULT NULL,
  `username` varchar(30) DEFAULT NULL,
  `password` varchar(30) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=gbk;

代码如下：

package test2;

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

/**
 * @author lee
 *
 */
public class DB {
	public static void main(String[] args) throws ClassNotFoundException, SQLException
	{
		//导入驱动包
		Class.forName("com.mysql.jdbc.Driver");
		//连接数据库
		String jdbc = "jdbc:mysql://localhost:3306/leetest?characterEncoding=GBK";
		//我的数据库信息，用户名：root,密码：123456
		Connection conn = null;
		conn = DriverManager.getConnection(jdbc, "root", "123456");
		Statement state = conn.createStatement();
		
		//增加记录
		String insertSql = "insert into user values('2','lance','1234')";
		state.executeUpdate(insertSql);
		//删除记录
		String deleteSql = "delete from user where username='lance'";
		state.executeUpdate(deleteSql);
		//修改记录
		String updateSql = "update user set password='123456' where username='1213'";
		state.executeUpdate(updateSql);
		//查询记录
		String sql = "select * from user";
		ResultSet rs = state.executeQuery(sql);
		while(rs.next())
		{	//getString（n）获取第n列的内容，数据库中的列数是从1开始的
			System.out.println(rs.getString(1)+","+rs.getString(2)+","+rs.getString(3));
		}
		//查询特定条件时，若想避免sql注入，可用以下方法
		String sql2 = "select * from user where id=? and username=?";
		PreparedStatement ps = conn.prepareStatement(sql2);
		ps.setString(1, "1");
		ps.setString(2, "shuai");
		ResultSet rs2 = ps.executeQuery();
		if(rs2.next())
		{
			System.out.println("pass:"+rs2.getString(3));
		}
		conn.close();

	}
	
	
}