Select earliest and latest dates between two columns that have the same ID in another column.

laganlee You can use this, paste this complete code in the Advanced Editor:

let
    Source = 
        Table.FromRows (
            Json.Document (
                Binary.Decompress (
                    Binary.FromText (
                        "i45WMjcxUdJRCvUGEgH5RSWl6Yk5QKaRgZGRroGhrqE5KidWB6YDSbFLal5uYlE2kkojA1QOQhtCLdhKnBpiAQ==",
                        BinaryEncoding.Base64
                    ),
                    Compression.Deflate
                )
            ),
            let
                _t = ( ( type nullable text ) meta [ Serialized.Text = true ] )
            in
                type table [
                    ID = _t,
                    DepartureCountry = _t,
                    ArrivalCountry = _t,
                    DepartureDateTime = _t,
                    ArrivalDateTime = _t
                ]
        ),
    ChangedType = 
        Table.TransformColumnTypes (
            Source,
            {
                { "ID", Int64.Type },
                { "DepartureCountry", type text },
                { "ArrivalCountry", type text },
                { "DepartureDateTime", type datetime },
                { "ArrivalDateTime", type datetime }
            }
        ),
    GroupedRows = 
        Table.Group (
            ChangedType,
            { "ID" },
            {
                {
                    "Result",
                    ( CurrentGroup ) =>
                        let
                            FirstArrival = Table.Min ( CurrentGroup, "ArrivalDateTime" ),
                            FirstArrivalDate = FirstArrival[ArrivalDateTime],
                            FirstArrivalCountry = FirstArrival[ArrivalCountry],
                            LastDepartureDate = Table.Max ( CurrentGroup, "DepartureDateTime" )[DepartureDateTime],
                            Result = Table.FromRecords (
                                {
                                    [
                                        ArrivalCountry    = FirstArrivalCountry,
                                        DepartureDateTime = LastDepartureDate,
                                        ArrivalDateTime   = FirstArrivalDate
                                    ]
                                }
                            )
                        in
                            Result,
                    type table [
                        ArrivalCountry = text,
                        DepartureDateTime = datetime,
                        ArrivalDateTime = datetime
                    ]
                }
            }
        ),
    ExpandedResult = 
        Table.ExpandTableColumn (
            GroupedRows,
            "Result",
            { "ArrivalCountry", "DepartureDateTime", "ArrivalDateTime" },
            { "ArrivalCountry", "DepartureDateTime", "ArrivalDateTime" }
        )
in
    ExpandedResult