c# - Linq 查询中的“IN”和 'NOT IN'

Question

我已经在 LINQPad 中测试了以下查询，它运行良好，但 VS2010 不喜欢它。

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));

我收到以下错误:

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));

这样做:

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

对您的原始查询执行相同的操作。