Excel Power Query - Count number of matching multiple columns - excel

Question

I have a datasource from an external Excel file that I have added to an Excel worksheet. I need to add new custom columns that compare the data to a table ("My_Table") in another worksheet that is manually updated. I used the Power Query Editor and created a new column that checks if there is a matching entry in My_Table based on matching 3 columns and gives a True/False result (ie for each row of the datasource, if the acctName, projectName, and boardName match a corresponding row in My_Table, then it returns true):
#"Added Custom" = Table.AddColumn(#"Reordered Columns", "Tracked", each Table.Contains( My_Table, [Customer=[acctName], Project=[projectName], Board=[boardName]]))
What I would like to do now is do the exact same thing but count how many times those three columns match in "My_Table". I thought Tabel.RowCount would work but I'm not sure if that's the right way to do it as I either have an error or a zero result.

Answer 1

dolomike, Here's another shot at it...
I started with this as Table1:
...and this as My_Table:
...and used this M code:
let
Source = Excel.CurrentWorkbook(){[Name="Table1"]}[Content],
#"Merged Queries" = Table.NestedJoin(Source, {"acctName", "projectName", "boardName"}, My_Table, {"Customer", "Project", "Board"}, "My_Table", JoinKind.LeftOuter),
#"Expanded My_Table" = Table.ExpandTableColumn(#"Merged Queries", "My_Table", {"Customer", "Project", "Board"}, {"My_Table.Customer", "My_Table.Project", "My_Table.Board"}),
#"Grouped Rows" = Table.Group(#"Expanded My_Table", {"My_Table.Customer", "My_Table.Project", "My_Table.Board"}, {{"Count", each Table.RowCount(_), type number}, {"AllData", each _, type table [acctName=text, projectName=text, boardName=text, My_Table.Customer=text, My_Table.Project=text, My_Table.Board=text]}}),
Custom2 = Table.TransformColumns(#"Grouped Rows",{"Count", each if _ = List.Max(#"Grouped Rows"[Count]) then 0 else _}),
#"Removed Other Columns" = Table.SelectColumns(Custom2,{"Count", "AllData"}),
#"Expanded AllData" = Table.ExpandTableColumn(#"Removed Other Columns", "AllData", {"acctName", "projectName", "boardName", "My_Table.Customer", "My_Table.Project", "My_Table.Board"}, {"acctName", "projectName", "boardName", "My_Table.Customer", "My_Table.Project", "My_Table.Board"}),
#"Removed Other Columns1" = Table.SelectColumns(#"Expanded AllData",{"Count", "acctName", "projectName", "boardName"}),
#"Reordered Columns" = Table.ReorderColumns(#"Removed Other Columns1",{"acctName", "projectName", "boardName", "Count"}),
#"Renamed Columns" = Table.RenameColumns(#"Reordered Columns",{{"acctName", "Customer"}, {"projectName", "Project"}, {"boardName", "Board"}}),
#"Removed Duplicates" = Table.Distinct(#"Renamed Columns")
in
#"Removed Duplicates"
...to get this result: