Need to create table basee on two different table

bgiri2430 
duplicate table A then create a Custom column in 
Table.AddColumn(#"Added Custom", "Table B", each TableB) give table name after that expand custom column and get you output.Thank You!!

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("Hca5DQAhEATBXMbG4MfmOQhitfmncVKXVWaaCkoxyYNp8cw3L/zwyj/e+OWdPz7k/gM=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Product = _t, #"Product ID" = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Product", type text}, {"Product ID", Int64.Type}}),
    #"Added Custom" = Table.AddColumn(#"Changed Type", "Table B", each TableB),
    #"Expanded Table B" = Table.ExpandTableColumn(#"Added Custom", "Table B", {"Category", "Category Id"}, {"Category", "Category Id"})
in
    #"Expanded Table B"

bgiri2430  I hope you getting my point.