sql-server - 排序依据和大小写

Question

我有以下 SQL 脚本:

ALTER PROC [dbo].[getRequests]
@SortBy             VARCHAR(50) = 'Date'
AS
SELECT  [ReqDate], [RequestorOrg], [RequestCategory],
        [ReqDescription], [OrgCountVote]
ORDER BY 
        CASE WHEN @SortBy = 'Date (oldest first)'   THEN [ReqDate]          END ASC, [OrgCountVote] DESC,
        CASE WHEN @SortBy = 'Date (newest first)'   THEN [ReqDate]          END DESC, [OrgCountVote] ,
        CASE WHEN @SortBy = 'Number of Votes'       THEN [OrgCountVote]     END DESC, reqdate,
        CASE WHEN @SortBy = 'Organisation'          THEN [RequestorOrg]     END,
        CASE WHEN @SortBy = 'Category'              THEN [RequestCategory]  END;

ORDER BY 中的前两种情况有多个要排序的列。

当我尝试保存脚本时，它会显示以下消息:

Msg 169, Level 15, State 1, Procedure getRequests, Line 8
A column has been specified more than once in the order by list. Columns in the order by list must be unique.

如何确保列是唯一的？

Answer 1

我建议您使用这种类型的存储过程:

ALTER PROC [dbo].[getRequests]
@SortBy             VARCHAR(50) = 'Date'
AS
BEGIN
DECLARE @sql varchar(max) 

SET @sql = 'SELECT  [ReqDate], [RequestorOrg], [RequestCategory], [ReqDescription], [OrgCountVote] ' +
           'ORDER BY ' +
                CASE @SortBy
                    WHEN 'Date (oldest first)' THEN '[ReqDate] ASC, [OrgCountVote] DESC'
                    WHEN 'Date (newest first)' THEN '[ReqDate] DESC, [OrgCountVote] '
                    WHEN 'Number of Votes'     THEN '[OrgCountVote] DESC, reqdate'
                    WHEN 'Organisation'        THEN '[RequestorOrg]'
                    WHEN 'Category'            THEN '[RequestCategory]'
                END
EXEC(@sql)
END