c# – Linq查询中的’IN’和’NOT IN’

发布时间：2020-12-15 08:39:30 所属栏目：百科来源：网络整理

导读：我在LINQPad中测试了以下查询,它运行正常,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.Streetlig

我在LINQPad中测试了以下查询,它运行正常,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.

解决方法

使用 Queryable.Any<TSource>.

而不是这个：

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

做这个：

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

对原始查询执行相同操作.

（编辑：李大同）

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