Create sequence based on another column

[Syndicate_Admin]

Hi guys, 

Could you help me with difficulty bellow?

I need create a sequence beginning  from 1 according with the column “Date", but when the column DONOR_ID change I need to restart the sequence from 1 again. 

 

[AlienSx]

Hi, @Syndicate_Admin your sequence is in "sequence" column after this step

    result = 
        Table.Combine(
            Table.Group(
                source_table, {"DONOR_ID"}, 
                {{"all", each Table.AddIndexColumn(Table.Sort(_, {"date"}), "sequence", 1, 1), 
                type table [date=nullable date, DONOR_ID=nullable text]}}
            )[all]
        )