Power Query as staging table - free Power BI account

Hi all,

I am not very good in M and Power Query so i decided to ask someone better than me 😉

The goal i would like to achive is to have staging table of prices per day from currency exchange web site.

I need to use free Power BI account to do it.

I was trying to create 2 tables:

1. Pull - this query is downloading data from web page at refresh

2. StagingCurrency - this is staging table

For staging I tried to do as follow:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i44FAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Currency = _t, Sell = _t, Buy = _t, Date = _t, Tag = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Currency", type text}, {"Sell", type number}, {"Buy", type number}, {"Date", type datetime}, {"Tag", type text}}),
    #"Appended Query" = Table.Combine({#"Changed Type", Pull}),
    Custom1 = #"Appended Query"
in
    Custom1

Table StagingCurrency is created as enter data -  i listed columns to match Pull table.

Expected logic is to load data for table from Pull and then add new values after next refresh without wiping out current data.

Currently result is that after refresh i have only latest data from Pull table, all previous data are cleared.

Best

K