Question

有人可以帮我编写一个LINQ查询来获取已加入的记录吗？我下面有两个型号。我希望得到属于给定项目的需求计数，并且有一个或多个ProjectTest加入它。

public class ProjectTest
{
    public int ProjectTestID { get; set; }
    public int ProjectID { get; set; }
    public String Objective { get; set; }
    public String Category { get; set; }
    public String SubCategory { get; set; }
    public String Tags { get; set; }
    public virtual ICollection<ProjectRequirement> ProjectRequirements { get; set; }
    public virtual ICollection<ProjectTestStep> ProjectTestSteps { get; set; }
}

public class ProjectRequirement
{
    public int ProjectRequirementID { get; set; }
    public int ProjectID { get; set; }

    [Display(Name = "Req No.")]
    public String ProjectRequirementIDStr { get; set; }

    [Display(Name = "Module")]
    public String ModuleName { get; set; }

    [Display(Name = "Description")]
    public String Description { get; set; }

    public virtual ICollection<ProjectTest> ProjectTests { get; set; }
}

我只是尝试按如下方式编写，但似乎没有用。

db.ProjectRequirements
  .Where(e => e.ProjectID == activeProjectID && 
              e.ProjectTests
                 .Select(ept => ept.ProjectTestID)
                 .Count() > 0)
  .Select(e => e.ProjectRequirementID)
  .Count();

Answer 1

目前，您正在计算具有给定ID并且至少有ProjectRequirement的{{1}}个对象的数量。

如果您想计算给定ProjectTest的{{1}} s的数量：

ProjectTest

LINQ查询获取连接记录的计数

1 个答案: