Linq查詢中的'IN'和'NOT IN'

Question

我在LINQPad中測試了以下查詢，它運行良好，但VS2010不喜歡它。

var topJobs = from j in streetlightDBEntities.Job 
    let mjobid = from m in streetlightDBEntities.Job.Include("Streetlight") 
       where m.Streetlight.StreetlightId == j.Streetlight.StreetlightId 
       orderby m.DateCompleted descending 
       select m.JobId 
     where mjobid.Take(5).Contains(j.JobId) 
     select j.JobId; 

var notTopJobs = streetlightDBEntities.Job.Where(c => !topJobs.Contains(c.JobId)); 

我得到了以下錯誤：

LINQ to Entities does not recognize the method 'Boolean Contains[String](System.Linq.IQueryable`1[System.String], System.String)' method, and this method cannot be translated into a store expression.

Answer 1

使用Queryable.Any<TSource>。

取而代之的是：

var notTopJobs = streetlightDBEntities 
     .Job 
     .Where(c => !topJobs.Contains(c.JobId)); 

這樣做：

var notTopJobs = streetlightDBEntities 
     .Job 
     .Where(c => !topJobs.Any(x => x.JobId == c.JobId)) 

執行相同的原始查詢。