linq to sql是否有關聯選項？

Question

我試圖將以下查詢移到Linq-to-sql，可能嗎？

select * from (
Select top (@Percent) percent with ties * 
from(
    Select distinct 
     LoanNumber as LoanNo 
    From CHE 
    Left Join RecordingInfo as Rec 
    On CHE.LoanNumber = Rec.LoanNo 
    Where Channel = 'LINX' 
     and CHE.Doc in ('MTG','MOD') 
     and Rec.LoanNo is null 
     and LoanNumber >= '@LoanNo' 
) A 
order by LoanNo @Order 
) B 
order by LoanNo 

我還沒有看到任何與linq關係。

Answer 1

我覺得像這樣的東西會爲你工作。

public static IQueryable<T> TopPercentWithTies<T, TKey>(this IOrderedQueryable<T> query, Expression<Func<T, TKey>> groupByExpression, double percent) 
{ 
    var groupedQuery = query.GroupBy(groupByExpression); 
    int numberToTake = groupedQuery.Count() * percent/100; 
    return groupedQuery.Take(numberToTake).SelectMany(t => t); 
} 

我只用了IEnumerable測試它，所以我不知道肯定它會與IQueryable的正常工作。我還在調用TopPercentWithTies（）之前對列表排序。

下面是我用來測試它的代碼。

int percent = 50; 
var people = new [] 
{ 
    new { Age = 99, Name = "Adam" }, 
    new { Age = 99, Name = "Andrew" }, 
    new { Age = 89, Name = "Bob" }, 
    new { Age = 50, Name = "Cecil" }, 
    new { Age = 50, Name = "Doug" }, 
    new { Age = 50, Name = "Everett" }, 
    new { Age = 35, Name = "Frank" }, 
    new { Age = 25, Name = "Greg" }, 
    new { Age = 15, Name = "Hank" } 
}; 
var sortedPeople = people.AsQueryable().OrderByDescending(person => person.Age); 
var results = sortedPeople.TopPercentWithTies(person => person.Age, percent); 
foreach (var person in results) 
    Console.WriteLine(person); 

希望它有助於或至少讓你在正確的方向。您可能需要調整計算numberToTake的邏輯。