查询将垂直更改为水平

Question

我有一个表Machine_Mode_Duration：

我需要一个查询，以便显示如下：

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Answer 1

您需要GROUP BY。

假设您有3种模式，并且在重复(Machine_id, INTERNAL_MODES)元组的情况下，可以总结一下INTERNAL_MODE_DURATION：

SELECT
    Machine_Id,
    SUM(CASE WHEN INTERNAL_MODES = 1 THEN INTERNAL_MODE_DURATION ELSE 0 END) AS Mode_1,
    SUM(CASE WHEN INTERNAL_MODES = 2 THEN INTERNAL_MODE_DURATION ELSE 0 END) AS Mode_2,
    SUM(CASE WHEN INTERNAL_MODES = 3 THEN INTERNAL_MODE_DURATION ELSE 0 END) AS Mode_3
FROM t
GROUP BY
    Machine_Id;

Answer 2

试试这个

select Machine_Id, 
       case when INTERNAL_MODES = 1 then INTERNAL_MODE_DURATION end as Mode_1,
       case when INTERNAL_MODES = 2 then INTERNAL_MODE_DURATION end as Mode_2,
       case when INTERNAL_MODES = 3 then INTERNAL_MODE_DURATION end as Mode_3
from Machine_Mode_Duration
group by Machine_Id
order by Machine_Id;

Answer 3

您可以像这样使用PIVOT

SELECT Machine_ID, 
[1] as Mode_1, [2] as Mode_2, [3] as Mode_3 FROM
(SELECT Machine_ID, Internal_Mode_Duration , InternalModes
    FROM Machine_Mode_Duration) AS SourceTable
PIVOT
(
Sum(Internal_Mode_Duration)
FOR InternalModes IN ([1], [2], [3])
) AS PivotTable;

您也可以通过CASE使用旧式方法，例如没有PIVOT命令的时间;）