如何在linq中跳过并采取工作

Question

我有以下Linq查询.它运作良好,但似乎令人困惑的是如何在linq中工作skip()和take()功能.这是我的查询

(from GRD in _tblAcademicYears.GetQueryable()
             where GRD.SchoolID == intSchoolID                 
             select new AcademicYearsModel
             {
                 AcademicYearID = GRD.AcademicYearID,
                 SchoolID = GRD.SchoolID,
                 AcademicYearName = GRD.AcademicYearName,
                 AcademicYearStart = GRD.AcademicYearStart,
                 AcademicYearEnd = GRD.AcademicYearEnd,
                 AcademicYearRemarks = GRD.AcademicYearRemarks,
                 IsActive = GRD.IsActive,
                 CreatedOn = GRD.CreatedOn,
                 CreatedBy = GRD.CreatedBy,
                 ModifiedOn = GRD.ModifiedOn,
                 ModifiedBy = GRD.ModifiedBy
             }
    ).Where(z => z.AcademicYearName.Contains(param.sSearch) || z.AcademicYearStart.ToString().Contains(param.sSearch)
    || z.AcademicYearEnd.ToString().Contains(param.sSearch) || z.AcademicYearRemarks.Contains(param.sSearch))
  .Skip(param.iDisplayStart).Take(param.iDisplayLength).ToList();

此查询如何从数据库获取记录.它会从数据库中获取所有记录,然后将应用skip()和take().或者它只是让拍摄与在限制skip()和take()

Answer 1

当你打电话时.仅限它,它只会转换为SQL:TOP N语法

当您调用.Skip和.一起使用时,它将生成至少2个查询,方法是使用ROWNUMBER过滤掉.

所以你的问题的简短答案是:不,它不会从数据库中获取所有记录.它将运行一个SQL来过滤和选择.

如果您很好奇,可以始终使用SQL事件探查器或只是在调试模式下检查生成的SQL.

这是一篇简单的MSDN文章解释它 https://msdn.microsoft.com/library/bb386988(v=vs.100).aspx