Question

我正面临一个复杂的情况，我知道可以解决问题的方法，但我的派生表中的order by子句搞乱了自定义排序。以下是我的输入和输出详细信息以及我尝试过的内容。

架构： - 输入： -

  CREATE TABLE Test( Rowname VARCHAR(10), Col1 DATETIME, Col2 DATETIME, Col3 DATETIME, Col4 DATETIME );

      INSERT INTO Test VALUES( 'Row1', '2016-01-14', '2016-01-08', '2016-01-30', '2016-01-01' );
      INSERT INTO Test VALUES( 'Row2', '2016-01-02', '2016-01-01', '2016-01-18', '2016-01-15' );

预期输出： -

RowName    Result
Row1       Col4,Col2,Col1,Col3
Row2       Col2,Col1,Col4,Col3

我尝试了什么？

WITH CTE(RowName,Colmn,RN) AS
(
SELECT RowName,Colmn,ROW_NUMBER() OVER( PARTITION BY RowName ORDER BY RowName )  AS RN 
         FROM
            ( 
              ( SELECT RowName,Col1 AS Col,'Col1' AS Colmn FROM Test )
                UNION ALL
              ( SELECT RowName,Col2 AS Col,'Col2' AS Colmn FROM Test )
                UNION ALL
              ( SELECT RowName,Col3 AS Col,'Col3' AS Colmn FROM Test )
                UNION ALL
              ( SELECT RowName,Col4 AS Col,'Col4' AS Colmn FROM Test )
             )  Z 
        ORDER BY RowName,Col 
)
SELECT RowName,
       MAX( ( CASE WHEN RN = 1 THEN Colmn END ) )  + ',' +
       MAX( ( CASE WHEN RN = 2 THEN Colmn END ) ) + ',' +
       MAX( ( CASE WHEN RN = 3 THEN Colmn END ) ) + ',' +
       MAX( ( CASE WHEN RN = 4 THEN Colmn END ) ) AS Result
  FROM CTE
GROUP BY RowName;

注意： -

内部查询/派生表中的ORDER BY RowName，Col子句失败，因为SQL Server中不允许这样做。如果我不使用此ORDER BY，那么如何在不使用ORDER BY子句的情况下执行自定义排序？

Answer 1

您的order by应在over子句中定义：

WITH CTE(RowName,Colmn,RN) AS
(
SELECT 
    RowName,Colmn,ROW_NUMBER() OVER( 
        PARTITION BY RowName 
        ORDER BY RowName, Col       -- add Col here
    ) AS RN 
    FROM
    ( 
      ( SELECT RowName,Col1 AS Col,'Col1' AS Colmn FROM Test )
        UNION ALL
      ( SELECT RowName,Col2 AS Col,'Col2' AS Colmn FROM Test )
        UNION ALL
      ( SELECT RowName,Col3 AS Col,'Col3' AS Colmn FROM Test )
        UNION ALL
      ( SELECT RowName,Col4 AS Col,'Col4' AS Colmn FROM Test )
     )  Z 
    -- ORDER BY RowName,Col -- remove this line
)
SELECT RowName,
       MAX( ( CASE WHEN RN = 1 THEN Colmn END ) )  + ',' +
       MAX( ( CASE WHEN RN = 2 THEN Colmn END ) ) + ',' +
       MAX( ( CASE WHEN RN = 3 THEN Colmn END ) ) + ',' +
       MAX( ( CASE WHEN RN = 4 THEN Colmn END ) ) AS Result
  FROM CTE
GROUP BY RowName;

Answer 2

如果你在row_number中将col添加到订单中，它将按你想要的顺序排序。

ROW_NUMBER() OVER( PARTITION BY RowName ORDER BY RowName, col )

Answer 3

x[, A := Reduce(function(x,y) paste(x,y,sep=","), .SD), .SDcols = columnsSelected]

执行自定义排序，其中包含派生表

3 个答案: