其他情況如何

Question

如何將ELSE子句添加到以下代碼中？

ROW_NUMBER() OVER (ORDER BY 
    CASE WHEN @OrderByColumn='ViewCount' AND @OrderDirection=0 THEN docsT.ViewCount END ASC,  
    CASE WHEN @OrderByColumn='AddedDate'AND @OrderDirection=0 THEN docsT.AddedDate END ASC, 
    CASE WHEN @OrderByColumn='AddedBy'AND @OrderDirection=0 THEN docsT.AddedBy END ASC, 
    CASE WHEN @OrderByColumn='Title' AND @OrderDirection=0 THEN docsT.Title END ASC 
) AS RowNum 

Answer 1

你可以把順序的外殼，然後選擇字段，你可以使用，你一個價值比較幾個值的情況下的形式。爲了支持升序和降序排序，你必須重複一遍。

order by 
    case when @OrderDirection = 0 then 
    case @OrderByColumn 
     when 'ViewCount' then docsT.ViewCount 
     when 'AddedDate' then docsT.AddedDate 
     when 'AddedBy' then docsT.AddedBy 
     when 'Title' then docsT.Title 
     else docsT.Title 
    end 
    end asc, 
    case when @OrderDirection = 1 then 
    case @OrderByColumn 
     when 'ViewCount' then docsT.ViewCount 
     when 'AddedDate' then docsT.AddedDate 
     when 'AddedBy' then docsT.AddedBy 
     when 'Title' then docsT.Title 
     else docsT.Title 
    end 
    end desc 

Answer 2

只需添加一些總是在最後評估爲真的東西。

我不知道你的要求是什麼，所以我猜ORDER BY：

ROW_NUMBER() OVER (ORDER BY 
    CASE WHEN @OrderByColumn='ViewCount' AND @OrderDirection=0 THEN docsT.ViewCount END ASC,  
    CASE WHEN @OrderByColumn='AddedDate'AND @OrderDirection=0 THEN docsT.AddedDate END ASC, 
    CASE WHEN @OrderByColumn='AddedBy'AND @OrderDirection=0 THEN docsT.AddedBy END ASC, 
    CASE WHEN @OrderByColumn='Title' AND @OrderDirection=0 THEN docsT.Title END ASC, 
    CASE WHEN 1 = 1 THEN docsT.Title END ASC 
) AS RowNum 

Answer 3

有許多方法：你可以在IsNull(...,docsT.Title)包住整個案件。或者你可以使用ELSE條款，如：

CASE WHEN OrderDirection = 0 THEN 
    CASE @OrderByColumn 
    WHEN 'ViewCount' THEN docsT.ViewCount 
    WHEN 'AddedDate' THEN docsT.AddedDate 
    WHEN 'AddedBy' THEN docsT.AddedBy 
    ELSE docsT.Title 
    END 
ELSE docsT.Title 
END