java对数据库的操作

package com.DateSystem;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.LinkedList;
import java.util.List;

import javax.swing.JOptionPane;

import com.gui.*;
public class Good_data {
	//根据商品名查询
	public List<Goods> findGoods(String sql){
		List<Goods> list=new LinkedList<Goods>();
		Statement stat=null;
		ResultSet rs=null;

		//获取和数据库的连接
		Connection conn=ConnectionDriver.getConnection();
		try {
			//生成Statement对象，封装SQL语句，执行查询
			stat=conn.createStatement();
			rs=stat.executeQuery(sql);
			//处理结果集中数据，读取每一条记录
			while(rs.next()){
				//int  id=rs.getInt(1);
				String  id=rs.getString(1);

				String name=rs.getString(2);
				String address=rs.getString(3);

				double  in_price=rs.getDouble(4);
				double  out_price=rs.getDouble(5);

				int  jinhuo=rs.getInt(6);
				int  chuhuo=rs.getInt(7);
				int  kucun=rs.getInt(8);

				Goods d=new Goods();

				d.setName(name);
				d.setId(id);
				d.setAddress(address);
				d.setIn_price(in_price);
				d.setOut_price(out_price);
				d.setKucun(kucun);
				d.setJinhuo(jinhuo);
				d.setChuhuo(chuhuo);
				list.add(d);			

			}
		} catch (SQLException e) {
			e.printStackTrace();
		}finally{
			JDBcloss.close(rs, stat, conn);
		}

		return list;
	}
	//依靠商品号查询
	public Goods findStudentById(String id){

		System.out.print("goods");
		//创建Data对象
		Goods data=new Goods();
		Statement stat=null;
		ResultSet rs=null;
		Connection conn=ConnectionDriver.getConnection();

		String sql="select  * from result where id='"+id+"'";
		try {
			stat=conn.createStatement();
			//执行查询
			rs=stat.executeQuery(sql);
			//处理结果集
			if(rs.next()){
				//int  id_id=rs.getInt(1);
				String  id_id=rs.getString(1);

				String name=rs.getString(2);
				String address=rs.getString(3);

				double  in_price=rs.getDouble(4);
				double  out_price=rs.getDouble(5);

				int  jinhuo=rs.getInt(6);
				int  chuhuo=rs.getInt(7);
				int  kucun=rs.getInt(8);

				data.setId(id_id);
				data.setName(name);
				data.setAddress(address);
				data.setIn_price(in_price);
				data.setOut_price(out_price);
				data.setKucun(kucun);
				data.setJinhuo(jinhuo);
				data.setChuhuo(chuhuo);

			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return data;
	}

   //对商品信息进行增加、修改、删除
	public boolean updateStudent(String sql){
		boolean flag=false;
		Statement stat=null;
		Connection conn=ConnectionDriver.getConnection();
		try {
			//生成Statement对象，向数据库发送sql指令
			stat=conn.createStatement();
			int i=stat.executeUpdate(sql);
			if(i>0){
				flag=true;
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}finally{
			JDBcloss.close(stat, conn);
		}

		return flag;
	}
}