If Statement with Custom column (yes or no)

Hello Shan_Drex12 

you can use Table.MatchAnyRows to do that. However I had to rename the columns before feeding this function. Here the code that contains both of your tables and the function i mentioned. Check it out

let
    Table1 = let
            Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMjI2t1DSUQrLLM7Mz1OK1YlWsrA0AIk45+SXZGTmpYPFjIwNDZFUxQIA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Number = _t, Sector = _t]),
            #"Changed Type" = Table.TransformColumnTypes(Source,{{"Number", Int64.Type}, {"Sector", type text}})
        in
            #"Changed Type",
    Table2 = let
            Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMjI2t1DSUQrLLM7Mz1OK1YlWMjE1A4k45+SXZGTmpYPFjIwNDZFUxQIA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [EntryNumber = _t, Sector = _t]),
            #"Changed Type" = Table.TransformColumnTypes(Source,{{"EntryNumber", Int64.Type}, {"Sector", type text}})
        in
            #"Changed Type",
    CheckTable2Matches = Table.AddColumn
    (
        Table1,
        "is entry in table 2",
        (add)=> Table.MatchesAnyRows(Table.RenameColumns(Table2, {{"EntryNumber", "Number"}}), each _ = add ),
        type logical
    )
in
    CheckTable2Matches

This is the output

Copy paste this code to the advanced editor in a new blank query to see how the solution works.

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Kudoes are nice too

Have fun

Jimmy