Array
(
    [110] => stdClass Object
        (
            [ID] => 113
            [post_title] => 2009-04-20 – Chris Haring – Coaching – Designed Body – Body vs Reality
            [calendar_date_start] => 20090420
            [calendar_date_end] => 20090420
            [calendar_project] => a:1:{i:0;s:3:"108";}
            [calendar_relation] => a:1:{i:0;s:3:"110";}
        )

    [111] => stdClass Object
        (
            [ID] => 211
            [post_title] => 2010-11-02 – Bruno Pocheron – Warsztat reżyserii światła
            [calendar_date_start] => 20101102
            [calendar_date_end] => 20101107
            [calendar_project] => a:1:{i:0;s:3:"108";}
            [calendar_relation] => a:1:{i:0;s:3:"111";}
        )

)

Tu też nie wiem jak tu robić aby każdy post wyświetlić tylko jednen raz z najstarszą datą w CF

Array
(
    [0] => stdClass Object
        (
            [ID] => 113
            [post_title] => 2009-04-20 – Chris Haring – Coaching – Designed Body – Body vs Reality
            [calendar_date_start] => 20090420
            [calendar_date_end] => 20090420
            [calendar_project] => a:1:{i:0;s:3:"108";}
            [calendar_relation] => a:1:{i:0;s:3:"110";}
        )

    [1] => stdClass Object
        (
            [ID] => 114
            [post_title] => 2009-04-24 – Chris Haring – Coaching – Designed Body – Body vs Reality
            [calendar_date_start] => 20090424
            [calendar_date_end] => 20090424
            [calendar_project] => 
            [calendar_relation] => a:1:{i:0;s:3:"110";}
        )

    [2] => stdClass Object
        (
            [ID] => 211
            [post_title] => 2010-11-02 – Bruno Pocheron – Warsztat reżyserii światła
            [calendar_date_start] => 20101102
            [calendar_date_end] => 20101107
            [calendar_project] => a:1:{i:0;s:3:"108";}
            [calendar_relation] => a:1:{i:0;s:3:"111";}
        )

    [3] => stdClass Object
        (
            [ID] => 227
            [post_title] => 2010-11-07 – Bruno Pocheron – Warsztat reżyserii światła
            [calendar_date_start] => 20101107
            [calendar_date_end] => 20101107
            [calendar_project] => 
            [calendar_relation] => a:1:{i:0;s:3:"111";}
        )

)