小编Mar*_*hio的帖子

我试图列出一些类别(父子关系),我有以下命令只列出父类别

context.Categories.Where(c => c.ParentId == null)

但是EF生成的sql查询不会返回任何内容

由EF生成的SQL查询

SELECT 
CAST(NULL AS int) AS [C1], 
CAST(NULL AS varchar(1)) AS [C2], 
CAST(NULL AS bit) AS [C3], 
CAST(NULL AS int) AS [C4]
FROM  ( SELECT 1 AS X ) AS [SingleRowTable1]
WHERE 1 = 0

类别模型

public class Category
{
  public int Id { get; set; }
  public string Name { get; set; }
  public bool IsActive { get; set; }
  public virtual IList<Category> SubCategories { get; set; }
  internal int? ParentId { …