Write update query in power query

Hi, I haven't used your logic, but result is the same as yours. Let me know if it works with real data.

Output:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("nZLBCsMgEET/xXOE3VlT12NK6TU99FAI+f/fqBFKqKklqyAMwmMeg8viKN0T8XTzdA3JB52iGxzlC0KgCMmRL5RPCSON7NahwfEPbnsT0TaEAySSSgiR/5TVkrpLwiKpPZK6SyaDJKhvycJZJTPUtSTQt2ThzJI4Lsk0Z+719AwJPjxm/ZKULX6+JFIb4Qaip1rY3sLWFiVzS4Wca4G9BVXL+gY=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [job_id = _t, step_id = _t, run_date = _t, run_time = _t, duration = _t]),
    ChangedType = Table.TransformColumnTypes(Source,{{"step_id", Int64.Type}, {"run_date", Int64.Type}, {"run_time", Int64.Type}, {"duration", Int64.Type}}),
    GroupedRows = Table.Group(ChangedType, {"job_id", "step_id"}, {{"All", each 
        [ a = Table.SelectRows(_, (x)=> x[step_id] = 0){0}?,
          b = Table.AddColumn(_, "schedule_id", (x)=> Text.From(a[run_date]?) & Text.PadStart(Text.From(a[run_time]?), 6, "0"), type text)
        ][b], type table}}, GroupKind.Local,
        (x,y)=> Number.From(y[step_id] = 0) ),
    Combined = Table.Combine(GroupedRows[All])
in
    Combined