loops - 电源查询循环

Question

我使用 Power Query 提取了过去一个月测试的所有独特项目类型:

let
  Source = Sql.Database("XXX", "YYY"),
  dbo_tblTest = Source{[Schema="dbo",Item="tblTest"]}[Data],
  #"Filtered Rows" = Table.SelectRows(dbo_tblTest, each Date.IsInPreviousNMonths([Test_Stop], 1)),
  #"Added Custom" = Table.AddColumn(#"Filtered Rows", "Custom", each Text.Start([Item],5)),
  #"Removed Duplicates" = Table.Distinct(#"Added Custom", {"Custom"})
in
  #"Removed Duplicates"

得到:

1. Test_ID --- Item --- Test_Start --- Test_Stop --- Custom
2. 2585048 --- B1846-6-02 --- 1/14/2014 12:46 --- 6/25/2015 14:28 --- B1846
3. 2589879 --- B1843-5-05 --- 12/23/2013 16:46 --- 6/25/2015 14:19 --- B1843
4. 2633483 --- B1907-1-04 --- 8/21/2014 20:47 --- 6/10/2015 6:20 --- B1907
5. 2638786 --- B1361-2-04 --- 6/13/2013 14:21 --- 6/16/2015 14:15 --- B1361
6. 2675663 --- B1345-2-02 --- 5/23/2014 18:39 --- 6/25/2015 21:27 --- B1345

接下来，我想使用 Power Query 为 Query1 中列出的每个项目类型提取过去 10 个测试，而不考虑时间段。我想出了如何分别提取项目类型的过去 10 个测试，但不是在一个查询中全部提取。

let
    Source = Sql.Database("XXX", "YYY"),
    dbo_tblTest = Source{[Schema="dbo",Item="tblTest"]}[Data],
    #"Filtered Rows" = Table.SelectRows(dbo_tblTest, each Text.StartsWith([Item], "B1846")),
    #"Sorted Rows" = Table.Sort(#"Filtered Rows",{{"Test_Stop", Order.Descending}}),
    #"Kept First Rows" = Table.FirstN(#"Sorted Rows",10)
in
    #"Kept First Rows"

得到:

1. Test_ID --- Item --- Test_Start --- Test_Stop --- Value
2. 11717643 --- B1846-6-02 --- 7/23/2015 12:48 --- 7/23/2015 12:57 --- 43725341
3. 11716432 --- B1846-1-21 --- 7/23/2015 10:23 --- 7/23/2015 10:29 --- 43724705
4. 11715802 --- B1846-1-21 --- 7/23/2015 9:28 --- 7/23/2015 10:29 --- 43724720
5. 11715505 --- B1846-1-21 --- 7/23/2015 8:59 --- 7/23/2015 9:06 --- 43724675
6. 11715424 --- B1846-1-21 --- 7/23/2015 8:36 --- 7/23/2015 8:59 --- 43724690
7. 11713680 --- B1846-1-55 --- 7/23/2015 5:50 --- 7/23/2015 6:07 --- 43725239
8. 11691169 --- B1846-6-04 --- 7/20/2015 22:47 --- 7/22/2015 20:18 --- 43642835
9. 11690466 --- B1846-6-04 --- 7/20/2015 21:30 --- 7/22/2015 18:41 --- 43642729
10. 11701183 --- B1846-1-140 --- 7/21/2015 21:34 --- 7/21/2015 22:24 --- 43667358
11. 11701184 --- B1846-6-04 --- 7/21/2013 20:35 --- 7/21/2015 20:46 --- 43667359

是否可以使用 Power Query 在一个查询中提取所有需要的数据？如果没有，是否可以将 VBA 与 Power Query 结合使用来完成它？

Answer 1

在 Power Query 中，如果您正在考虑如何循环，您通常会发现一个高阶库函数可以满足您的需求。在本例中，它是分组。

分组按某个键拆分表，在您的例子中是第一个表的 Custom 列。您可以使用 Table.TransformColumns 将“保持过去 10”逻辑重写为您在每个分组表中应用的函数，然后将分组表扩展回一个平面表。

您的查询应该是这样的:

let
  Source = Sql.Database("XXX", "YYY"),
  dbo_tblTest = Source{[Schema="dbo",Item="tblTest"]}[Data],
  #"Added Custom" = Table.AddColumn(dbo_tblTest, "Custom", each Text.Start([Item],5)),
  #"Grouped Rows" = Table.Group(#"Added Custom", {"Custom"}, {{"Grouped", each _, type table}}),
  Custom2 = Table.TransformColumns(#"Grouped Rows", {{"Grouped", (groupedTable) =>
      let
          #"Sorted Rows" = Table.Sort(groupedTable,{{"Test_Stop", Order.Descending}}),
          #"Kept First Rows" = Table.FirstN(#"Sorted Rows",10)
      in
          #"Kept First Rows"}}),
  #"Removed Other Columns1" = Table.SelectColumns(Custom2,{"Grouped"}),
  #"Expanded Grouped" = Table.ExpandTableColumn(#"Removed Other Columns1", "Grouped", Table.ColumnNames(#"Added Custom"))
in
  #"Expanded Grouped"