existsell.java

教材订购系统

package program;

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

public class ExistSell {

	public ExistSell()  {

		}
	public String YOrN(String bno,String bcount) throws ClassNotFoundException, SQLException{
		String DBDriver="sun.jdbc.odbc.JdbcOdbcDriver";
		String connectionStr="jdbc:odbc:Driver={Microsoft Access Driver (*.mdb)}; DBQ=D:/Java_Work/BookManager/program/db/bookmanage.mdb";
		Connection con = null;
		Statement stmt = null;
		ResultSet rs = null;
		
		Class.forName(DBDriver);	 //加载驱动器
		con=DriverManager.getConnection(connectionStr,"",""); //连接数据库
		stmt=con.createStatement();   //创建Statement对象
		rs=stmt.executeQuery("Select * From 书_inf Where 书号='"+bno+"'");  //查询 书_inf

		if(rs.next())//书_inf有记录
		{
			rs=stmt.executeQuery("Select * From   库存 Where 书号='"+bno+"'");
			if(rs.next())//有库存
			{
				if(rs.getInt("数量")>=Integer.parseInt(bcount))//存量足够
				{
					return "YY";
				}
				else //存量不够
				{
					return "YN";
				}	
			}
			else//库存为零(属于存量不够)
			{
				return "YN";
			}
		}
		else//书_inf没有记录
		{
			rs=stmt.executeQuery("Select * From   库存 Where 书号='"+bno+"'");
			if(rs.next())
			{
				return "Error";
			}
			else
			{
				return "N*";
			}
		}
		/*
		if(rs1.next() && rs2.next()) //一览表中存在记录 并且 库存中有存量
		{
			if(rs2.getInt("数量")>=Integer.parseInt(bcount))//存量足够
			{
				return "YY";
			}
			else //存量不够
			{
				return "YN";
			}	
		}
		else if(rs1.next() && !rs2.next())//一览表中存在记录 并且(但是) 没有库存(库存为0)
		{
			return "YN";	
		}
		else if(!rs1.next() && !rs2.next())//一览表中没有记录
		{
			return "N*";
		}
		else
		{
			
			return "Error";
		}
		*/		
	}
}