Question

我有以下代码我有3个表作为Department，DepartmentTask和DepartmentPosition。以下是表格：

public partial class Department()
{
   public int DepartmentId { get; set; }
   public string DepartmentName { get; set; }
   public Nullable<int> ParentDepartmentId { get; set; }    
}
public partial class DepartmentPosition
{
    public int PositionId { get; set; }
    public int DepartmentId { get; set; }
    public string PositiontName { get; set; }        
}
public partial class DepartmentTask
{
    public int TaskId { get; set; }
    public int DepartmentId { get; set; }
    public string TaskName { get; set; }       
}

因此，任何部门都可以成为其他部门（任务和职位）的父母。所以在这里我想根据DepartmentId从表中选择所有记录，这些记录是特定部门的子项。

var z = from n in dbbs.Department
        select new
        {
            deptcount = dbbs.Department.Count(p => p.ParentDepartmentId == id),
            poscount = dbbs.DepartmentPosition.Count(x => x.DepartmentId == id),
            taskcount = dbbs.DepartmentTask.Count(t => t.DepartmentId == id)
        };
if(z.Count()>0)
{ 
//do something
}
else
{

}

现在如果表格中没有记录，那么它就会进入if块。我想知道如果根据查询没有记录，如何限制。

Answer 1

我不确定你要用select语句实现什么。你不能用：

var deptcount = dbbs.Department.Count(p => p.ParentDepartmentId == id);
var poscount = dbbs.DepartmentPosition.Count(x => x.DepartmentId == id);
var taskcount = dbbs.DepartmentPosition.Count(t => t.DepartmentId == id);

if(deptcount > 0) 
{
 //do something
}

如果您尝试根据部门进行分组，请解释，我会更新我的答案。

Answer 2

var count= from s in ObjectContext.tb1
                              join c in ObjectContext.tb2 on s.ParentCategoryID equals c.PersonCategoryID
                              join p in ObjectContext.tb3 on c.BusinessEntityID equals p.BusinessEntityID
                              select new count()
                              {
                                 tbl1count =c.count()
                                 tbl2count =p.count()
                                 tbl3count =p.count()
                              };

然后

if(count.tbl1count.any()){
//do whatever you need}

如何从linq中的select new子句中选择记录

2 个答案: