如果在WHERE子句中存在

Question

這天我遇到了一個問題。在我的MS SQL數據庫中，我有一個文章表（他們的詳細信息，如插入日期，插入用戶和其他工作人員）和一個表與多種語言的文章正文。我希望文章正文處於用戶首選語言。但並非所有文章都是用所有語言寫成的。所以，會很好，首先要用用戶首選語言搜索文章，如果不存在，用第一種語言獲取文章。

爲此，我使用了一個函數。 WHERE子句是這樣的：

WHERE [tblBody].[Language] = @Language AND 
     [tblTitle].[Language] = @Language 

，但將是很好，如果它會是這樣： SELECT（如果身體是我的首選語言獲得該機構;其他給我一個（也許我的理解是））

我希望你明白我想做什麼，女巫是我的問題。

預先感謝您！

UPDATE

這是我這就需要修改實際查詢：

ALTER FUNCTION [fx_GetNews] 
( 
    @MinimumPermission INT, 
    @UserID UNIQUEIDENTIFIER, 
    @OwnerID UNIQUEIDENTIFIER = NULL, 
    @Title NVARCHAR(250) = NULL, 
    @Body VARCHAR(150) = NULL, 
    @InsertDateStart DATETIME = NULL, 
    @InsertDateEnd DATETIME = NULL, 
    @CreatedByUserID UNIQUEIDENTIFIER = NULL, 
    @ExpirationDate DATETIME = NULL, 
    @Language VARCHAR(150) 
) 
RETURNS @News TABLE 
(
    [Id] UNIQUEIDENTIFIER 
    ,[OwnerID] UNIQUEIDENTIFIER 
    ,[Title] NVARCHAR(250) 
    ,[TitlePictureUrl] VARCHAR(150) 
    ,[Body] NVARCHAR(max) 
    ,[Visible] BIT 
    ,[InsertDate] DATETIME 
    ,[CreatedByUserId] UNIQUEIDENTIFIER 
    ,[ModifiedDate] DATETIME 
    ,[ModifiedByUserId] UNIQUEIDENTIFIER 
    ,[ModifiedByPerson] VARCHAR(250) 
    ,[ExpirationDate] DATETIME 
    ,[CreatedByPerson] VARCHAR(250) 
    ,[Permission] INT 
) 
AS 
BEGIN 
    INSERT INTO @News 
      ([Id] 
      ,[OwnerID] 
      ,[Title] 
      ,[TitlePictureUrl] 
      ,[Body] 
      ,[Visible] 
      ,[InsertDate] 
      ,[CreatedByUserId] 
      ,[ModifiedDate] 
      ,[ModifiedByUserId] 
      ,[CreatedByPerson] 
      ,[ModifiedByPerson] 
      ,[ExpirationDate] 
      ,[Permission]) 
     SELECT 
       [dbo].[tblNews].[Id] 
       ,[dbo].[tblNews].[OwnerID] 
       ,CAST([tblTitle].[Text] AS VARCHAR(150)) 
       ,[dbo].[tblNews].[TitlePictureUrl] 
       ,[tblBody].[Text] 
       ,[dbo].[tblNews].[Visible] 
       ,[dbo].[tblNews].[InsertDate] 
       ,[dbo].[tblNews].[CreatedByUserId] 
       ,[dbo].[tblNews].[ModifiedDate] 
       ,[dbo].[tblNews].[ModifiedByUserId] 
       ,[dbo].[tblNews].[CreatedByPerson] 
       ,[dbo].[tblNews].[ModifiedByPerson] 
       ,[dbo].[tblNews].[ExpirationDate] 
       ,[eportofolii].[fx_GetPermissionForObject] (@UserID, [dbo].[tblNews].[ID], 1, 1) 
      FROM [dbo].[tblNews] 
        INNER JOIN [dbo].[tblAdmTranslateText] AS [tblBody] ON 
         [tblBody].[OwnerID] = [dbo].[tblNews].[ID] 
        INNER JOIN [dbo].[tblAdmTranslateText] AS [tblTitle] ON 
         [tblTitle].[OwnerID] = [dbo].[tblNews].[ID] 
     WHERE 
      [eportofolii].[fx_GetPermissionForObject] (@UserID, [dbo].[tblNews].[ID], 1, 1) >= @MinimumPermission AND 
      ([dbo].[tblNews].[OwnerID] = ISNULL(@OwnerID, [dbo].[tblNews].[OwnerID]) OR [dbo].[tblNews].[OwnerID] IS NULL) AND 
      [tblTitle].[Text] LIKE '%' + ISNULL(@Title, '') + '%' AND 
      [tblBody].[Text] LIKE '%' + ISNULL(@Body, '') + '%' AND 
      ([dbo].[tblNews].[InsertDate] BETWEEN ISNULL(@InsertDateStart, ([dbo].[tblNews].[InsertDate] - 7)) AND ISNULL(@InsertDateEnd, [dbo].[tblNews].[InsertDate] + 1)) AND 
      [dbo].[tblNews].[CreatedByUserID] = ISNULL(@CreatedByUserID, [dbo].[tblNews].[CreatedByUserID]) AND 
      ([dbo].[tblNews].[ExpirationDate] > ISNULL(@ExpirationDate, GETDATE() - 1) OR [dbo].[tblNews].[ExpirationDate] IS NULL) AND 
      [tblBody].[UDF_2] = 'Body' AND 
      [tblTitle].[UDF_2] = 'Title' AND 
      [tblBody].[UDF_1] = 'News' AND 
      [tblTitle].[UDF_1] = 'News' AND 
      [tblBody].[Language] = @Language AND 
      [tblTitle].[Language] = @Language 
     ORDER BY [InsertDate] DESC 
    RETURN 
END 

的問題是在這裏結束：

[tblBody].[Language] = @Language AND 
[tblTitle].[Language] = @Language 

謝謝！

Answer 1

一種選擇是使用MSSQL 「COALESCE」 功能：

• http://msdn.microsoft.com/en-us/library/ms190349.aspx

另一種可能是使用一個CASE塊。

Answer 2

你想做的事情有點複雜。您希望以所需語言（如果存在）返回文章，否則返回其他語言。

爲此，窗口功能是非常有用的：如果首選語言不可用

select t.* 
from (select blah, 
      max(case when [tblBody].[Language] = @Language then 1 else 0 end) over (partition by article) as HasLanguage  
     from whatever 
     where [tblTitle].[Language] = @Language 
    ) t 
where HasLanguage = 1 or [tblBody].[Language] <> @Language 

Answer 3

;WITH x AS 
(
    SELECT b.[Language], /* other columns from b */ 
    rn = ROW_NUMBER() OVER (PARTITION BY b.article_id_of_some_kind 
     ORDER BY CASE WHEN t.[Language] = @Language THEN 1 ELSE 2 END) 
    FROM dbo.tblBody AS b 
    INNER JOIN dbo.tblLanguage AS l 
    ON b.LanguageID = l.LanguageID -- guessing here 
) 
SELECT /* cols */ FROM x WHERE rn = 1; 

這將返回一個任意語言。您可以通過修改內部ORDER BY來進一步優化。

Answer 4

select B.* 
from bodies as B 
where exists (
    select 1 from (
    select b.article, coalesce(u.language, b.language) as language 
    from bodies as b 
    left join users as u 
    on b.language = u.language 
    and u.user = @user 
    where b.article = @article 
    and b.default_language = 'TRUE' -- or whatever 
) as A 
    on A.article = B.Article 
    and A.language = B.language 
) 

您必須在兩種語言中進行選擇：用戶的語言和文章的語言。你可以使用UNION或​​3210（因爲外連接是一種聯合），後者更簡單。