PQ - Comparing two columns in the same table and returning unmatched

(question from the web)

Quote:

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Looking to find all the rows where column B does NOT match column A

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Source					Result
ColumnA	ColumnB	Data1	Data2		ColumnA	NotMatchB	Data1	Data2
USNTS	USNTS	ABC	123		USNTS	USSPZ	ABC	123
USNTS	USSPZ	ABC	123		USNTS	USLVV	ABC	123
USNTS	USLVV	ABC	123		USNTS	USLVV	ABC	123
USNTS	USLVV	ABC	123		USNTS	USLVV	ABC	123
USNTS	USLVV	ABC	123		USNTS	USLVV	ABC	123
USNTS	USLVV	ABC	123		USNTS	USLVV	ABC	123
USNTS	USLVV	ABC	123		USNTS	USLVV	ABC	123
USNTS	USLVV	ABC	123		USNTS	USLVV	ABC	123
USNTS	USLVV	ABC	123		USNTS	USLVV	ABC	123
USNTS	USLVV	ABC	123		USLVV	USNYC	ABC	123
USMSY	USMSY	ABC	123
USHOU	USHOU	ABC	123
USMSY	USMSY	ABC	123
USMSY	USMSY	ABC	123
USLVV	USNYC	ABC	123
USNYC	USNYC	ABC	123

Code:

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let
    Source = Excel.CurrentWorkbook(){[Name="Table1"]}[Content],
    Diff = Table.AddColumn(Source, "NotMatchB", each List.Difference({[ColumnB]},{[ColumnA]})),
    Expand = Table.ExpandListColumn(Diff, "NotMatchB"),
    Filter = Table.SelectRows(Expand, each ([NotMatchB] <> null)),
    TSC = Table.SelectColumns(Filter,{"ColumnA", "NotMatchB", "Data1", "Data2"})
in
    TSC

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