CASE 中的排序依据和不同类型 [英] Order by and Different Types in a CASE

问题描述

我需要根据参数中的整数输入对结果集进行排序.

I have a requirement to order a result set by a column, based on an Integer input into a parameter.

问题是，我需要为 OrderBy 使用 CASE，而且代码似乎接受 case 列中的第一个TYPE"......任何其他类型都失败.

Problem is, I need to use a CASE for the OrderBy, and it seems the code accepts the first 'TYPE' in the case column... any other types fail.

我的代码是这样的:

    WITH error_table AS  
 (  
  SELECT Row_Number() OVER   
   (ORDER BY  
        CASE @orderBy
            WHEN 1 THEN received_date  -- Last Rx'd message  
            WHEN 2 THEN message_id -- Message Id  
            WHEN 3 THEN zibmat.short_name -- Message action type  
            WHEN 4 THEN error_action.short_name -- Status type  
            WHEN 5 THEN ime.[allocated_date] -- Allocated Date  
            ELSE received_date
    END) AS RowNumber   

   ,ime.[ijis_message_error_id]  
      ,ime.[message_id]  
      ,ime.[message_version] 

因此，当 OrderBy 为 1 时，它会起作用.它按 rx_date 排序...但是当我向它发送 2 时，它因数据时间转换错误而失败.

So, when OrderBy is 1, it works. It sorts by rx_date... but when I sent it a 2, it fails with a data time conversion error.

看起来所有类型都必须相同...

It looks like all the types must be the same...

发送 5 可以正常工作，因为那也是约会时间.

Sending a 5 works fine, as that's a date time too.

有什么办法可以解决这个问题吗?

Is there a way I can fix this?

推荐答案

CASE 语句只能解析为一种数据类型.这与您知道@orderby 只会选择一个分支并且它将是特定数据类型这一事实无关.

A CASE statement must resolve to only one data type. This is regardless of the fact that you know that @orderby will choose only one branch and it will be a particular data type.

你可以使用这样的东西，虽然笨重但可以工作.

You could use something like this, which would be clunky but will work.

ORDER BY
CASE @orderBy WHEN 1 THEN received_date -- Last Rx'd message
WHEN 2 THEN 0
WHEN 3 THEN 0
WHEN 4 THEN 0
WHEN 5 THEN ime.[allocated_date] -- Allocated Date
ELSE received_date END,
CASE @orderBy WHEN 1 THEN 0
WHEN 2 THEN message_id -- Message Id
WHEN 3 THEN 0
WHEN 4 THEN 0
WHEN 5 THEN 0
ELSE 0 END,
CASE @orderBy WHEN 1 THEN ''
WHEN 2 THEN ''
WHEN 3 THEN zibmat.short_name -- Message action type
WHEN 4 THEN error_action.short_name -- Status type
WHEN 5 THEN ''
ELSE '' END

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