使我的SQL查询变为动态

Question

我的表有一个ID int（PK），然后是col1-col32字符串。我的专栏中的价值与时间不同。有时候有时会填满10个等等。我可以使这个SQL动态，所以我不必填满我所有的32列？

WITH CTE 
AS 
(
    SELECT * 
    FROM 
    (
     SELECT ID, 
       Column_Name, 
       ROW_NUMBER() OVER (PARTITION BY ID ORDER BY col) row_num, 
       val 
     FROM tPivot A 
     INNER JOIN (SELECT Column_Name AS COLUMN_NAME, ORDINAL_POSITION FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'tPivot') B 
     ON A.ID = B.ORDINAL_POSITION - 1 
     UNPIVOT 
     (
      val for col in (col1,col2,col3,col4,col5) 
     ) unpvt 
    ) A 
    PIVOT 
    (
     MAX(val) FOR column_name IN (col1,col2,col3,col4,col5) 
    ) pvt 
) 

SELECT * 
FROM 
(
    SELECT ID, 
      row_num, 
      coalesce(col1,col2,col3,col4,col5) val 
    FROM cte 
) A 
PIVOT 
(
    MAX(val) FOR ID IN ([1],[2],[3],[4],[5]) 
) pvt 

Answer 1

很好。 建设的ID为查询（我的意思是([1],[2],[3],[4],[5])）的PIVOT部分使用：

DECLARE @IDP AS NVARCHAR(MAX) 
SELECT @IDP = STUFF((SELECT ',' + QUOTENAME(ID) 
        from (select distinct row_num as ID from CTE) q 
        group by q.ID 
        order by q.ID 
      FOR XML PATH(''), TYPE 
      ).value('.', 'NVARCHAR(MAX)') 
     ,1,1,'') 

，现在你可以在dynamic sql使用它：

DECLARE @sql AS NVARCHAR(MAX) 
SET @sql=' 
WITH CTE 
AS 
(
    SELECT * 
    FROM 
    (
     SELECT ID, 
       Column_Name, 
       ROW_NUMBER() OVER (PARTITION BY ID ORDER BY col) row_num, 
       val 
     FROM tPivot A 
     INNER JOIN (SELECT Column_Name AS COLUMN_NAME, ORDINAL_POSITION FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = ''tPivot'') B 
     ON A.ID = B.ORDINAL_POSITION - 1 
     UNPIVOT 
     (
      val for col in (col1,col2,col3,col4,col5) 
     ) unpvt 
    ) A 
    PIVOT 
    (
     MAX(val) FOR column_name IN (col1,col2,col3,col4,col5) 
    ) pvt 
) 

SELECT * 
FROM 
(
    SELECT ID, 
      row_num, 
      coalesce(col1,col2,col3,col4,col5) val 
    FROM cte 
) A 
PIVOT 
(
    MAX(val) FOR ID IN ('+@IDP+') 
) pvt' 
EXEC(@sql) 

的基础架构和SQLFIDDLE DEMO您查询你在评论中提到的小提琴演示。

注：也许你原来的查询可以更优化，我只是想说如何使它，并为所有的IDS（行）动态SQL使用