我可以将SQL Server排序顺序存储在变量中吗？

Question

我在存储过程中有以下SQL。有没有一种方法可以删除IF语句，并将’ASC’/’DESC’选项作为变量传递？

我知道我可以用多种不同的方式进行查询，或者返回一个表并在外部对其进行排序等。我只想知道是否可以避免重复CASE语句。

IF @sortOrder = 'Desc'
  BEGIN
    SELECT * FROM #t_results
    ORDER BY
    CASE WHEN @OrderBy = 'surname'           THEN surname END DESC,
    CASE WHEN @OrderBy = 'forename'          THEN forename END DESC,
    CASE WHEN @OrderBy = 'fullName'          THEN fullName END DESC,
    CASE WHEN @OrderBy = 'userId'            THEN userId END DESC,
    CASE WHEN @OrderBy = 'MobileNumber'      THEN MSISDN END DESC,
    CASE WHEN @OrderBy = 'DeviceStatus'      THEN DeviceStatus END DESC,
    CASE WHEN @OrderBy = 'LastPosition'      THEN LastPosition END DESC,
    CASE WHEN @OrderBy = 'LastAlert'         THEN LastAlert END DESC,
    CASE WHEN @OrderBy = 'LastCommunication' THEN LastCommunication END DESC,
    CASE WHEN @OrderBy = 'LastPreAlert'      THEN LastPreAlert END DESC 
    END
 ELSE
   BEGIN
    SELECT * FROM #t_results
    ORDER BY
    CASE WHEN @OrderBy = 'surname'           THEN surname END DESC,
    CASE WHEN @OrderBy = 'forename'          THEN forename END DESC,
    CASE WHEN @OrderBy = 'fullName'          THEN fullName END DESC,
    CASE WHEN @OrderBy = 'userId'            THEN userId END DESC,
    CASE WHEN @OrderBy = 'MobileNumber'      THEN MSISDN END DESC,
    CASE WHEN @OrderBy = 'DeviceStatus'      THEN DeviceStatus END DESC,
    CASE WHEN @OrderBy = 'LastPosition'      THEN LastPosition END DESC,
    CASE WHEN @OrderBy = 'LastAlert'         THEN LastAlert END DESC,
    CASE WHEN @OrderBy = 'LastCommunication' THEN LastCommunication END DESC,
    CASE WHEN @OrderBy = 'LastPreAlert'      THEN LastPreAlert END DESC 
    END
END

Answer 1

传入@OrderBy int，其中正数是ASC，负数是DESC，实际数字是要排序的列

SELECT
    dt.yourColumn1
        ,dt.yourColumn2
        ,dt.yourColumn3
        ,CASE 
            WHEN @OrderBy>0 THEN dt.SortBy
            ELSE NULL
         END AS SortByAsc
        ,CASE 
            WHEN @OrderBy<0 THEN dt.SortBy
            ELSE NULL
         END AS SortByDesc
    FROM (SELECT
              yourColumn1
                  ,yourColumn2
                  ,yourColumn3
                  ,CASE
                      WHEN ABS(@OrderBy) = 1 THEN surname
                      WHEN ABS(@OrderBy) = 2 THEN forename
                      WHEN ABS(@OrderBy) = 3 THEN fullName
                      WHEN ABS(@OrderBy) = 4 THEN CONVERT(varchar(10),userId)
                      WHEN ABS(@OrderBy) = 5 THEN CONVERT(varchar(10),MobileNumber
                      WHEN ABS(@OrderBy) = 6 THEN DeviceStatus
                      WHEN ABS(@OrderBy) = 7 THEN LastPosition
                      WHEN ABS(@OrderBy) = 8 THEN CONVERT(varchar(23),LastAlert,121)
                      WHEN ABS(@OrderBy) = 9 THEN CONVERT(varchar(23),LastCommunication,121)
                      WHEN ABS(@OrderBy) =10 THEN CONVERT(varchar(23),LastPreAlert,121)
                      ELSE NULL
                  END AS SortBy
              FROM YourTablesHere
              WHERE X=Y
         ) dt
    ORDER BY SortByAsc ASC, SortByDesc DESC

只需确保您构建的字符串能够正确排序，请注意，我使用’YYYY-MM-DD
hh：mm：ss.mmm’作为日期，并将数字放入字符串中。我们通常将多个列放在一起，因此，如果您按姓氏排序，也使用姓氏，等等。请注意，如果您合并多个列，则需要用零或空格填充。

如果您不希望将SortByAsc和SortByDesc列包含在结果集中，请将整个内容包装在派生表中。