Question

我要检查此特定房间是否已经预订：

bool overlaps = false;

这种方法只能找到值为roomId的 first 5，因为它是FirstOrDefault();

var room = (from u in db.Reservation
             where u.RoomId == roomId
             select u  
           ).FirstOrDefault();

if((StartDateWantToBook <= room.EndDate) && (room.StartDate <= EndDateWantToBook))
{
     overlaps = true;
     MessageBox.Show("This room is already reserved");
}
else
{
   // Process to reserv this room
overlaps = false;
}

但是，如果我的roomId在具有不同开始和结束日期的多行中的值为5，我认为我必须改用Tolist()。也许像这样：

var room = (from u in db.Reservation
            where u.RoomId == roomId
            select u  
           ).Tolist();

问题：

如何检查每个 roomId的值为5，然后防止在同一房间中重叠日期？

我尝试了以下操作，但有时不起作用...

foreach(var item in room)
{
  if((StartDateWantToBook <= item.EndDate) && (item.StartDate <= EndDateWantToBook))
  {
       overlaps = true;
       MessageBox.Show("This room is already reserved");
  }
  else
  {
      // Process to reserv this room
      overlaps = false;
  }

Answer 1

else块将overlaps设置为false。即使存在重叠的保留，如果它处理的最后一个保留不重叠，它也会被设置为false。摆脱else块。

Answer 2

首先，请更改代码以提高可读性

bool overlaps = false;
foreach(var item in room)
{
  if((StartDateWantToBook <= item.EndDate) && ( EndDateWantToBook >= item.StartDate))
     {
        overlaps = true;
        MessageBox.Show("This room is already reserved");
        // or you could use break; here to exist 
     }
}
// you could continue here by checking if(overlaps)

使用此方法，您可以删除else块以减少一些编码行。

c＃查询重叠日期

2 个答案: