Question

如何将ELSE子句添加到以下代码中？

 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

您可以将订单放在外壳中，然后为了选择字段，您可以使用将一个值与多个值进行比较的情况的形式。要支持升序和降序排序，您必须重复这一切。

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

只需在最后添加总是评估为true的内容。

我不知道你的要求是什么，所以我在猜测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

有很多方法：你可以将整个案例包装在IsNull(...,docsT.Title)中。或者您可以使用ELSE子句，例如：

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

ELSE在案件中

3 个答案: