Question

使用代码优先迁移来生成数据库。

我有这样的亲子关系，每个人都有孩子，孩子可能有自己的孩子等。

public class Person
{
    public string Name { get; set; }
    public bool Flagged { get; set; }
    public virtual ICollection<Person> Children { get; set; }
    public virtual Person Master { get; set; }
    ...
}

找到这些东西的最有效方法是什么？到目前为止，我一直在使用递归查询，这似乎很慢，并不是一件好事。我读到了公用表格表达式，但我不确定这是否符合我的需求并支持EF 代码首次迁移。

人找到第一个具有Flagged = true的Master。
人找到所有嵌套的孩子。
Person查找所有已标记= true的嵌套子项。

Answer 1

AFAIK实体框架不支持公用表表达式。您应该继续使用数据库视图。对我来说，让父母和孩子的问题看起来像这样。

    WITH Children AS 
 (
  SELECT a.*
  FROM dbo.Persons a
  WHERE Id = 14
  UNION ALL
  SELECT a.*
  FROM dbo.Persons a JOIN Children c ON a.IdParentPerson = c.id
  )
  SELECT *
  FROM Children 
  /*WHERE Children.Flagged = true*/ /*IF REQUIRED*/

和

    WITH Parents AS 
 (
  SELECT a.*
  FROM dbo.Persons a
  WHERE Id = 16
  UNION ALL
  SELECT a.*
  FROM dbo.Persons a JOIN Parents c ON a.Id = c.IdParentPerson
  )
  SELECT *
  FROM Parents
  WHERE Parents.Flagged = true

然后在像

这样的DbSet上使用它

var id = YOUR_ID;
using(var context = new Context())
{
    var query = context.Set<GroupEntity>().SqlQuery(
    " WITH Parents AS  " +
    " ( " +
    " SELECT a.* " +
    " FROM dbo.Persons a " +
    " WHERE Id = @Id " +
    " UNION ALL " +
    " SELECT a.* " +
    " FROM dbo.Persons a JOIN Parents c ON a.Id = c.IdParentPerson " +
    " ) " +
    " SELECT * " +
    " FROM Parents " +
    " WHERE Parents.Flagged = true "
    , new SqlParameter("@Id", id));  
}

EF5代码首次迁移在嵌套层次结构

1 个答案: