C# 如何在列表中搜索LINQ SQL where值

我有一个名为Quotes的SQL表

在C中，我的用户：

Public class Locations
{ 
 public string cityname { get; set; }
}

 List<Locations> = new puLocations List<Locations>  // Pickup Locations
 List<Locations> = new delLocations List<Locations> // Delivery Locations

现在我想用这些列表搜索报价表。。像这样的事情显然是行不通的

var quotes = from q in db.Quotes
where q.PULocations in puLocations  //puLocatiosn is the list<Locations>
and q.DELLocations in delLocations
select q;

所以我想让它返回任何匹配项。。如果在普州，我有黄金海岸，悉尼，布里斯班。交货地点我有珀斯，霍巴特 它应该返回黄金海岸->珀斯 黄金海岸->霍巴特 悉尼->珀斯 悉尼->黄金海岸 .... 等等，如果这些引号存在，首先你需要这个

List<Locations> puLocations= new  List<Locations>()  // Pickup Locations  
List<Locations> delLocations = new  List<Locations>() // Delivery Locations 

首先你需要这个

List<Locations> puLocations= new  List<Locations>()  // Pickup Locations  
List<Locations> delLocations = new  List<Locations>() // Delivery Locations 

---

为了不让你的生活变得更艰难，你应该在db中进行这个操作，我打赌你的数据库中有收货和发货位置以及报价 因此，假设您有像db.Locations.Wherel=>l.type==DEL和db.Locations.Wherel=>l.type==PU这样的查询，您将编写以下查询

var quotes = from q in db.Quotes
    join del in db.Locations on del equals q.DELLocations
    join pu in db.Locations on pu equals q.PULocations
    where pu.type == PU && del.type == DEL && otherConditions
    select q;

此外，若数据库中确实存在约束，它们将作为导航属性传播，所以linq查询如下所示

var quotes = from q in db.Quotes where q.DELLocation.field == something && q.PULocation.field == something

但您可能没有约束，所以第一个查询将是最佳选择

最后一种方法是在语句中使用实体SQL，并编写如下所示的长语句

   // you build string specifying as many parameters as you have items in your lists
   var entitySQL = "select quote FROM [Quotes] WHERE quote.DELLocation.LocationID IN (@delparam1, @delparam2,.... ) AND quote.PULocation.LocationID in (@puparam1, @puparam2,.... )"
   // then you create ObjectParameterCollection to substitute your IDs to ObjectQuery
   var opc = new ObjectParameterCollection();
   opc.Add("@delparam1", DELLocation[0].LocationID) // obviously you'll do it using linq
   opc.Add("@puparam1", PULocation[0].LocationID)

   // create object query

   var quotes = db.CreateQuery<Quote>(entitySQL, opc);

---

为了不让你的生活变得更艰难，你应该在db中进行这个操作，我打赌你的数据库中有收货和发货位置以及报价 因此，假设您有像db.Locations.Wherel=>l.type==DEL和db.Locations.Wherel=>l.type==PU这样的查询，您将编写以下查询

var quotes = from q in db.Quotes
    join del in db.Locations on del equals q.DELLocations
    join pu in db.Locations on pu equals q.PULocations
    where pu.type == PU && del.type == DEL && otherConditions
    select q;

此外，若数据库中确实存在约束，它们将作为导航属性传播，所以linq查询如下所示

var quotes = from q in db.Quotes where q.DELLocation.field == something && q.PULocation.field == something

但您可能没有约束，所以第一个查询将是最佳选择

最后一种方法是在语句中使用实体SQL，并编写如下所示的长语句

   // you build string specifying as many parameters as you have items in your lists
   var entitySQL = "select quote FROM [Quotes] WHERE quote.DELLocation.LocationID IN (@delparam1, @delparam2,.... ) AND quote.PULocation.LocationID in (@puparam1, @puparam2,.... )"
   // then you create ObjectParameterCollection to substitute your IDs to ObjectQuery
   var opc = new ObjectParameterCollection();
   opc.Add("@delparam1", DELLocation[0].LocationID) // obviously you'll do it using linq
   opc.Add("@puparam1", PULocation[0].LocationID)

   // create object query

   var quotes = db.CreateQuery<Quote>(entitySQL, opc);

Contains不是LINQ扩展方法；它一直存在于长列表中。Contains不是LINQ扩展方法；它一直在那个里，就像那个长长的清单一样。