Re: How to define multiple data sources for a single dataset in power BI report.

 - Try something like this in your query. This uses a parameter called "Environment" that can either be "Dev" or "Prod"

let
    DevSource = Csv.Document(File.Contents("C:\temp\powerbi\test_dev.csv"),[Delimiter=",", Columns=2, Encoding=1252, QuoteStyle=QuoteStyle.None]),
    ProdSource = Csv.Document(File.Contents("C:\temp\powerbi\test_prod.csv"),[Delimiter=",", Columns=2, Encoding=1252, QuoteStyle=QuoteStyle.None]),
    #"Promoted Headers Dev" = Table.PromoteHeaders(DevSource),
    #"DevResult" = Table.TransformColumnTypes(#"Promoted Headers Dev",{{"Column1", type text}, {"Column2", Int64.Type}}),

    #"Promoted Headers Prod" = Table.PromoteHeaders(ProdSource),
    #"ProdResult" = Table.TransformColumnTypes(#"Promoted Headers Prod",{{"Column1", type text}, {"Column2", Int64.Type}}),

    result = 
        if Environment = "Dev"
        then #"DevResult"
        else #"ProdResult"
in
    #"result"