calldao.java~6~

火车订票。。 只有部分代码。实现功能是基本的查询和订购功能

package trainticket.Dao;
import java.sql.*;
import trainticket.Bean.*;
/**
  数据库访问层
 */
public class CallDao
{
     DBCOnn dbConn;
       public CallDao()
     {
         dbConn=new DBCOnn();

    }
      public boolean SelectTrainOrder(String trainNum)//检查车次是否在数据库中存在
      {
        try {
            PreparedStatement ptrt = this.dbConn.getConn().prepareStatement(
                    "select TrainNo from TrainTicket where TrainNo=?");
            ptrt.setString(1,trainNum);
            ResultSet res=ptrt.executeQuery();
            if(res.next())
            {
                return true;
            }
        } catch (SQLException ex)
        {
            ex.printStackTrace();
        }
            return false;
      }
      public String compareAmount(Info info)//检测订购数量
      {
          try {
            PreparedStatement ptrt = this.dbConn.getConn().prepareStatement(
                    "select ?,? from TrainTicket where TrainNo=?");
            ptrt.setString(1,info.getSeatBed());//设置查询 床还是 坐
            ptrt.setString(2,info.getPrice());//设置查询的单价
            ptrt.setString(3,info.getTrainNumber());//设置车次
            ResultSet res=ptrt.executeQuery();//执行
            while(res.next())
            {
                  if(res.getInt(1)<info.getNumber())
                  {
                      return "Sorry,订购失败，车票数量不足";
                  }
                  else
                  {
                      return "车票订购成功，请支付："+(new Float(res.getInt(1)*res.getFloat(2)).toString())+"元";
                  }

            }
        } catch (SQLException ex)
        {
            ex.printStackTrace();
        }
            return "";

      }


}