实体框架和 ASP.NET MVC 应用程序的自定义 Linq 查询

Question

我一直在使用实体框架开发 ASP.NET MVC 应用程序。另外，这是我第一次开发 ASP.NET MVC 应用程序。我一直在努力（近一个月的尝试和谷歌搜索）编写一个 linq 查询以在 jQuery 数据表中显示以下 SQL 查询的结果。它涉及各种左连接，并且某些列具有空值。如果有人可以帮助我解决这个问题，那就太好了。下面有3张表

1. 资产
2. 类别
3. 期限

SELECT 
    Asset.Name AS Name,
    Asset.Type AS Type,
    Asset.Parent_Asset AS "Parent Asset",
    Cat.Category AS Category,
    Cat.Parent_Category AS "Parent Category",
    T.BUSINESS_TERM AS "Business Term",
    T.SHORT_DESCRIPTION AS Description
FROM 
    (SELECT 
         CH.DISPLAY AS Name,
         CH.TYPE AS Type,
         PA.DISPLAY AS Parent_Asset,
         CH.CATEGORY_INT_ID
     FROM 
         [Metadata].[dbo].[Asset] CH
     LEFT JOIN 
         [Metadata].[dbo].[Asset] PA ON PA.PARENT_ASSET_ID = CH.ASSET_INT_ID) Asset
     LEFT JOIN 
         (SELECT
              CH.DISPLAY AS Category,
              PA.DISPLAY AS Parent_Category,
              CH.CATEGORY_INT_ID AS Category_Id
          FROM 
              [METADATA].[dbo].[Category] CH
          LEFT JOIN 
              [METADATA].[dbo].[Category] PA ON PA.PARENT_CATEGORY_ID = CH.CATEGORY_INT_ID) Cat ON Asset.CATEGORY_INT_ID = Cat.Category_Id
     LEFT JOIN 
         [Metadata].[dbo].[Term] T ON T.CATEGORY_INT_ID = Cat.Category_Id

Answer 1

在应用程序连接的数据库中创建存储过程

CREATE PROCEDURE sp_GetAsset
AS
BEGIN

SELECT 
    Asset.Name AS Name,
    Asset.Type AS Type,
    Asset.Parent_Asset AS ParentAsset,
    Cat.Category AS Category,
    Cat.Parent_Category AS ParentCategory,
    T.BUSINESS_TERM AS BusinessTerm,
    T.SHORT_DESCRIPTION AS Description
FROM 
(
    SELECT 
        CH.DISPLAY AS Name,
        CH.TYPE AS Type,
        PA.DISPLAY AS Parent_Asset,
        CH.CATEGORY_INT_ID
    FROM 
        [Metadata].[dbo].[Asset] CH
    LEFT JOIN 
        [Metadata].[dbo].[Asset] PA ON PA.PARENT_ASSET_ID = CH.ASSET_INT_ID) Asset
    LEFT JOIN 
        (SELECT
             CH.DISPLAY AS Category,
             PA.DISPLAY AS Parent_Category,
             CH.CATEGORY_INT_ID AS Category_Id
         FROM 
             [METADATA].[dbo].[Category] CH
         LEFT JOIN 
             [METADATA].[dbo].[Category] PA ON PA.PARENT_CATEGORY_ID = CH.CATEGORY_INT_ID) Cat ON Asset.CATEGORY_INT_ID = Cat.Category_Id
    LEFT JOIN 
        [Metadata].[dbo].[Term] T ON T.CATEGORY_INT_ID = Cat.Category_Id
);  
END

创建类以获取数据：

public class TestAsset
{
        public string Name           { get; set; }
        public string Type           { get; set; }
        public string ParentAsset    { get; set; }
        public string Category       { get; set; }
        public string ParentCategory { get; set; }
        public string BusinessTerm   { get; set; }
        public string Description    { get; set; }
}

在您的上下文中获取数据

 public class YourContext : DbContext
 {
    public List<TestAsset> GetAssets()
    {
        return this.Query<TestAsset>.FromSql("Exec sp_GetAsset").ToList();
    }
 }

使用 GetAssets 方法

using (YourContext context = new YourContext())
{       
   var list = context.GetAssets();
}