Combine columns from different datasets

karelstoel I guess these are two tables with different column names, there are many ways to do this. You can use append queries in Power Query and for this, you need to make sure the column name are the same, rename the columns and then use append and that will do it.

karelstoel  if you have a table like this called new

| date       | value |
|------------|-------|
| 2021-01-02 | 1000  |
| 2021-01-02 | 2000  |
| 2021-01-03 | 3000  |

  and a table like this called old

| date       | value |
|------------|-------|
| 2021-01-01 | 100   |
| 2021-01-01 | 200   |
| 2021-01-02 | 400   |

 and if you choose to create a new table through DAX that would generate all the distinct date and combined values, this is how you can do it

Table =
VAR _0 =
    DISTINCT ( UNION ( VALUES ( new[date] ), VALUES ( old[date] ) ) )
VAR _1 =
    ADDCOLUMNS (
        _0,
        "val",
            SUMX ( FILTER ( new, new[date] = EARLIER ( [date] ) ), new[value] )
                + SUMX ( FILTER ( old, old[date] = EARLIER ( [date] ) ), old[value] )
    )
RETURN
    _1

Hi karelstoel 

Please see this PBIX file for a solution

If your columns have different names (as you've shown) then you could use Power Query to merge these columns using code like this

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMjJUcEtNKipNLKpUMDIwNFfSUYIgEwtLPVMDpVgdoBoDHGoM9AwgKiBcYxMDCxM9SyMQDypqaKHgVZoD1mYJ4hpZ6hmbIcsbKziWppcWl8BVmFiagkwFKYkFAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Factuur.Factuurdatum = _t, Order_Date = _t, Service_Entry_Revenue_WIP = _t, Gefactureerd = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Factuur.Factuurdatum", type date}, {"Order_Date", type date}, {"Service_Entry_Revenue_WIP", type number}, {"Gefactureerd", type number}}),
    #"Added Custom" = Table.AddColumn(#"Changed Type", "DateCol", each if [Factuur.Factuurdatum] is null then [Order_Date] else [Factuur.Factuurdatum]),
    #"Added Custom1" = Table.AddColumn(#"Added Custom", "NumberCol", each if [Service_Entry_Revenue_WIP] is null then [Gefactureerd] else [Service_Entry_Revenue_WIP]),
    #"Changed Type1" = Table.TransformColumnTypes(#"Added Custom1",{{"DateCol", type date}, {"NumberCol", type number}})
in
    #"Changed Type1"

Basically, it checks (for example) both date columns and takes the value from whatever column is not blank.  Then does the same for the numeric columns. 

Giving this

Note that you have a row where there is no date in either of the date columns in which case you'll get no date in the merged column too.

Regards

Phil