Question

我有2张桌子。问题是无论我做什么，我都会得到多条记录。

页
子菜单

关系是1到1（每个子菜单都有一个页面）

SubMenus示例数据：

submenu_id  parentmenu_id   display_name    url_name
----------------------------------------------------
    1           1           Home            home    
    2           1           Contact         contact

Pages表数据：

page_id     submenu_id      page_title          url_name
---------------------------------------------------------
   1            1           Home Page           home    
   2            1           Contact Page        null

我想从那里SubMenu.UrlName == Home

(from s in SubMenus
 join p in Pages on s.Id equals p.SubMenuId
 where s.UrlName == "home"
 select new 
          {
              s.Id, s.UrlName,
              PageId = p.Id, p.Title, p.Html, 
              p.MetaAuthor, p.MetaKeywords, p.MetaDescription 
          }).FirstOrDefault();

但是，如果我检查SQL并运行它。我没有任何问题得到单一记录。下面是SQL生成的内容

SELECT TOP (1) 
    [Extent1].[submenu_id] AS [submenu_id], 
    [Extent1].[url_name] AS [url_name], 
    [Extent2].[page_id] AS [page_id], 
    [Extent2].[page_title] AS [page_title], 
    [Extent2].[page_html] AS [page_html], 
    [Extent2].[meta_author] AS [meta_author], 
    [Extent2].[meta_keywords] AS [meta_keywords], 
    [Extent2].[meta_description] AS [meta_description]
FROM  
    [dbo].[SubMenu] AS [Extent1]
INNER JOIN 
    [dbo].[Pages] AS [Extent2] ON [Extent1].[submenu_id] = [Extent2].[submenu_id]
WHERE 
    N'home' = [Extent1].[url_name]

表格结构：

CREATE TABLE [dbo].[ParentMenu]
(
    [parentmenu_id] [int] IDENTITY(1,1) NOT NULL,
    [group_name] [nvarchar](50) NULL,
    [title] [nvarchar](100) NULL,
    [active] [bit] NOT NULL,
    [index_order] [int] NULL,

    CONSTRAINT [PK_ParentMenu] 
        PRIMARY KEY CLUSTERED ([parentmenu_id] ASC)
                    WITH (PAD_INDEX = OFF, STATISTICS NORECOMPUTE = OFF, 
                          IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, 
                          ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]
GO

ALTER TABLE [dbo].[ParentMenu] 
    ADD CONSTRAINT [DF_ParentMenu_active] DEFAULT ((1)) FOR [active]
GO

ALTER TABLE [dbo].[ParentMenu] 
    ADD CONSTRAINT [DF_ParentMenu_index_order] DEFAULT ((0)) FOR [index_order]
GO

CREATE TABLE [dbo].[SubMenu]
(
    [submenu_id] [int] IDENTITY(1,1) NOT NULL,
    [parentmenu_id] [int] NOT NULL,
    [display_name] [nvarchar](100) NULL,
    [url_name] [nvarchar](100) NULL,
    [index_order] [int] NULL,
    [active] [bit] NOT NULL,

    CONSTRAINT [PK_SubMenu] 
        PRIMARY KEY CLUSTERED ([submenu_id] ASC)
                    WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, 
                    IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, 
                    ALLOW_PAGE_LOCKS = ON) ON [PRIMARY],

    CONSTRAINT [IX_SubMenu_1] 
        UNIQUE NONCLUSTERED ([url_name] ASC)
                    WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, 
                    IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, 
                    ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]
GO

ALTER TABLE [dbo].[SubMenu] WITH CHECK 
    ADD CONSTRAINT [FK_SubMenu_ParentMenu] 
        FOREIGN KEY([parentmenu_id]) REFERENCES [dbo].[ParentMenu] ([parentmenu_id])
             ON DELETE CASCADE
GO

ALTER TABLE [dbo].[SubMenu] CHECK CONSTRAINT [FK_SubMenu_ParentMenu]
GO

ALTER TABLE [dbo].[SubMenu] 
    ADD CONSTRAINT [DF_SubMenu_index_order] DEFAULT ((0)) FOR [index_order]
GO

ALTER TABLE [dbo].[SubMenu] 
    ADD CONSTRAINT [DF_SubMenu_active]  DEFAULT ((1)) FOR [active]
GO

CREATE TABLE [dbo].[Pages]
(
    [page_id] [int] IDENTITY(1,1) NOT NULL,
    [submenu_id] [int] NOT NULL,
    [page_title] [nvarchar](200) NULL,
    [url_name] [nvarchar](100) NULL,
    [page_html] [nvarchar](max) NULL,
    [meta_author] [nvarchar](300) NULL,
    [meta_keywords] [nvarchar](max) NULL,
    [meta_description] [nvarchar](max) NULL,
    [active] [bit] NOT NULL,
    [creation_date] [date] NULL,

    CONSTRAINT [PK_Pages] 
        PRIMARY KEY CLUSTERED ([page_id] ASC)
                    WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE = OFF, 
                          IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, 
                          ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO

ALTER TABLE [dbo].[Pages] WITH CHECK 
    ADD CONSTRAINT [FK_Pages_SubMenu] 
        FOREIGN KEY([submenu_id]) REFERENCES [dbo].[SubMenu] ([submenu_id])
             ON DELETE CASCADE
GO

ALTER TABLE [dbo].[Pages] CHECK CONSTRAINT [FK_Pages_SubMenu]
GO

ALTER TABLE [dbo].[Pages] 
    ADD CONSTRAINT [DF_Pages_active] DEFAULT ((1)) FOR [active]
GO

Answer 1

您说的是Problem is I always get multiple records no matter what I do.

您显示的查询在第一行中有top 1，它将始终只返回一行。

它出了什么问题？

从我看到你的SQL查询与你的LINQ查询所做的匹配。

在这种情况下，LINQ查询不可能返回比SQL返回更多的行。

LINQ查询问题：返回多条记录

1 个答案: