C# eed应该在钥匙里

更新2:通过嵌入子查询，您可能可以简化一些事情：

var q = from c in CUS_Contact
        select new {
                       c.Id,
                       c.Cus_Id, 
                       c.Namefirst, 
                       c.Namemiddle, 
                       c.Namelast, 
                       Phones = (from cp in CUS_Phone_JCT
                                 where c.Id == cp.Contact_Id
                                 select cp.Phone.Phone),
                       c.Title, 
                       c.Dept, 
                       c.Des, c.Datecreate, 
                       c.Dateupdate, 
                       c.Usr_idcreate, 
                       c.Usr_idupdate
                   };

---

我对电话不太清楚。电话也是。它将输出表名“CUS_Phone”，除非我添加第二个表名。这个查询非常有效，只不过它需要4秒，而之前的查询只需要不到十分之一秒。有什么想法吗？生成的SQL看起来像什么？它太大了，无法在这里输入。限制为600个字符，大约4000个字符。您可以使用SQL的摘录更新该问题。我很好奇它使用的是什么子查询。按组合键分组就是问题所在！我自己也在用你给我的东西做一些事情。谢谢你的帮助！ -- Region Parameters DECLARE @p0 Int SET @p0 = 4 -- EndRegion SELECT ( SELECT [t8].[id] FROM ( SELECT TOP (1) [t6].[id] FROM [CUS_Contact] AS [t6] LEFT OUTER JOIN [CUS_Phone_JCT] AS [t7] ON [t6].[id] = [t7].[Contact_Id] WHERE [t2].[id] = [t6].[id] ) AS [t8] ) AS [Id], ( SELECT [t11].[Cus_Id] FROM ( SELECT TOP (1) [t9].[Cus_Id] FROM [CUS_Contact] AS [t9] LEFT OUTER JOIN [CUS_Phone_JCT] AS [t10] ON [t9].[id] = [t10].[Contact_Id] WHERE [t2].[id] = [t9].[id] ) AS [t11] ) AS [Cus_Id], ( SELECT [t14].[namefirst] FROM ( SELECT TOP (1) [t12].[namefirst] FROM [CUS_Contact] AS [t12] LEFT OUTER JOIN [CUS_Phone_JCT] AS [t13] ON [t12].[id] = [t13].[Contact_Id] WHERE [t2].[id] = [t12].[id] ) AS [t14] ) AS [Namefirst], ( SELECT [t17].[namemiddle] FROM ( SELECT TOP (1) [t15].[namemiddle] FROM [CUS_Contact] AS [t15] LEFT OUTER JOIN [CUS_Phone_JCT] AS [t16] ON [t15].[id] = [t16].[Contact_Id] WHERE [t2].[id] = [t15].[id] ) AS [t17] ) AS [Namemiddle], ( SELECT [t20].[namelast] FROM ( SELECT TOP (1) [t18].[namelast] FROM [CUS_Contact] AS [t18] LEFT OUTER JOIN [CUS_Phone_JCT] AS [t19] ON [t18].[id] = [t19].[Contact_Id] WHERE [t2].[id] = [t18].[id] ) AS [t20] ) AS [Namelast], ( SELECT [t23].[title] FROM ( SELECT TOP (1) [t21].[title] FROM [CUS_Contact] AS [t21] LEFT OUTER JOIN [CUS_Phone_JCT] AS [t22] ON [t21].[id] = [t22].[Contact_Id] WHERE [t2].[id] = [t21].[id] ) AS [t23] ) AS [Title], ( SELECT [t26].[dept] FROM ( SELECT TOP (1) [t24].[dept] FROM [CUS_Contact] AS [t24] LEFT OUTER JOIN [CUS_Phone_JCT] AS [t25] ON [t24].[id] = [t25].[Contact_Id] WHERE [t2].[id] = [t24].[id] ) AS [t26] ) AS [Dept], ( SELECT [t29].[des] FROM ( SELECT TOP (1) [t27].[des] FROM [CUS_Contact] AS [t27] LEFT OUTER JOIN [CUS_Phone_JCT] AS [t28] ON [t27].[id] = [t28].[Contact_Id] WHERE [t2].[id] = [t27].[id] ) AS [t29] ) AS [Des], ( SELECT [t32].[datecreate] FROM ( SELECT TOP (1) [t30].[datecreate] FROM [CUS_Contact] AS [t30] LEFT OUTER JOIN [CUS_Phone_JCT] AS [t31] ON [t30].[id] = [t31].[Contact_Id] WHERE [t2].[id] = [t30].[id] ) AS [t32] ) AS [Datecreate], ( SELECT [t35].[dateupdate] FROM ( SELECT TOP (1) [t33].[dateupdate] FROM [CUS_Contact] AS [t33] LEFT OUTER JOIN [CUS_Phone_JCT] AS [t34] ON [t33].[id] = [t34].[Contact_Id] WHERE [t2].[id] = [t33].[id] ) AS [t35] ) AS [Dateupdate], ( SELECT [t38].[usr_idcreate] FROM ( SELECT TOP (1) [t36].[usr_idcreate] FROM [CUS_Contact] AS [t36] LEFT OUTER JOIN [CUS_Phone_JCT] AS [t37] ON [t36].[id] = [t37].[Contact_Id] WHERE [t2].[id] = [t36].[id] ) AS [t38] ) AS [Usr_idcreate], ( SELECT [t41].[usr_idupdate] FROM ( SELECT TOP (1) [t39].[usr_idupdate] FROM [CUS_Contact] AS [t39] LEFT OUTER JOIN [CUS_Phone_JCT] AS [t40] ON [t39].[id] = [t40].[Contact_Id] WHERE [t2].[id] = [t39].[id] ) AS [t41] ) AS [Usr_idupdate], [t2].[id] AS [id2] FROM ( SELECT [t0].[id] FROM [CUS_Contact] AS [t0] LEFT OUTER JOIN [CUS_Phone_JCT] AS [t1] ON [t0].[id] = [t1].[Contact_Id] GROUP BY [t0].[id] ) AS [t2] WHERE (( SELECT [t5].[Cus_Id] FROM ( SELECT TOP (1) [t3].[Cus_Id] FROM [CUS_Contact] AS [t3] LEFT OUTER JOIN [CUS_Phone_JCT] AS [t4] ON [t3].[id] = [t4].[Contact_Id] WHERE [t2].[id] = [t3].[id] ) AS [t5] )) = @p0 GO -- Region Parameters DECLARE @x1 Int SET @x1 = 9327 -- EndRegion SELECT [t2].[phone] AS [value] FROM [CUS_Contact] AS [t0] LEFT OUTER JOIN [CUS_Phone_JCT] AS [t1] ON [t0].[id] = [t1].[Contact_Id] LEFT OUTER JOIN [CUS_Phone] AS [t2] ON [t2].[id] = [t1].[Phone_Id] WHERE @x1 = [t0].[id] GO -- Region Parameters DECLARE @x1 Int SET @x1 = 9328 -- EndRegion SELECT [t2].[phone] AS [value] FROM [CUS_Contact] AS [t0] LEFT OUTER JOIN [CUS_Phone_JCT] AS [t1] ON [t0].[id] = [t1].[Contact_Id] LEFT OUTER JOIN [CUS_Phone] AS [t2] ON [t2].[id] = [t1].[Phone_Id] WHERE @x1 = [t0].[id]

var q = from c in CUS_Contact
        join cp in CUS_Phone_JCT on c.Id equals cp.Contact_Id into cp2 
        from cp3 in cp2.DefaultIfEmpty()
        group new { c, cp3.Phone.Phone } by c.Id into g
        let c = g.First().c
        select new {
                       c.Id,
                       c.Cus_Id, 
                       c.Namefirst, 
                       c.Namemiddle, 
                       c.Namelast, 
                       Phones = g.Select(x => x.Phone)
                       c.Title, 
                       c.Dept, 
                       c.Des, c.Datecreate, 
                       c.Dateupdate, 
                       c.Usr_idcreate, 
                       c.Usr_idupdate
                   };

foreach(var v in q) {
    Console.WriteLine(v.Id + "-" + v.Namefirst);
    foreach(var p in v.Phones) {
        Console.WriteLine(" -" + p);
    }
}

var q = from c in CUS_Contact
        join cp in CUS_Phone_JCT on c.Id equals cp.Contact_Id into cp2 
        from cp3 in cp2.DefaultIfEmpty()
        group new { c, cp3.Phone.Phone } by c.Id into g
        let c = g.First().c
        select new {
                       c.Id,
                       c.Cus_Id, 
                       c.Namefirst, 
                       c.Namemiddle, 
                       c.Namelast, 
                       Phones = g.Select(x => x.Phone)
                       c.Title, 
                       c.Dept, 
                       c.Des, c.Datecreate, 
                       c.Dateupdate, 
                       c.Usr_idcreate, 
                       c.Usr_idupdate
                   };

        group cp3.Phone.Phone
          by new { c.Id, c.Cus_Id, c.Namefirst, ETC } into g
        let c = g.Key
        select new {
                       ...
                       Phones = g.Select(p => p),
                       ...
                   }

var q = from c in CUS_Contact
        select new {
                       c.Id,
                       c.Cus_Id, 
                       c.Namefirst, 
                       c.Namemiddle, 
                       c.Namelast, 
                       Phones = (from cp in CUS_Phone_JCT
                                 where c.Id == cp.Contact_Id
                                 select cp.Phone.Phone),
                       c.Title, 
                       c.Dept, 
                       c.Des, c.Datecreate, 
                       c.Dateupdate, 
                       c.Usr_idcreate, 
                       c.Usr_idupdate
                   };