变量占位符数量错误（$ wpdb-> prepare + ON DUPLICATE KEY UPDATE）

My query is supposed to insert a row when there isn't already an existing one, but I don't know how to put the parameters correctly. There are 8 parameters which go into a new row, but if doing an update only 6 columns should be updated. But when doing update it says I provided the wrong amount of variable placeholders , 14 placeholders for 8 variables. See here:

    $event_id       =   "value";
    $status_type    =   "value";
    $sport_name     =   "value";
    $startdate      =   "value";
    $ut             =   "value";
    $name           =   "value";
    $value_home     =   "value";
    $value_away     =   "value";

    $sql = "INSERT INTO wp_mytable "
    . "(event_id,status_type, sport_name, startdate, ut, name, value_home, value_away) "
    . "VALUES (%s,%s,%s,%s,%s,%s,%s,%s) "
    . "ON DUPLICATE KEY UPDATE status_type = %s, startdate = %s,ut = %s, name = %s, value_home = %s, value_away = %s";

    $sql = $wpdb->prepare($sql,$event_id, $status_type,$sport_name,$startdate,$ut ,$name ,$value_home ,$value_away );

    $wpdb->query($sql);

The VALUES placeholders are needed for inserts I guess, but they also count towards the "on duplicate key" updates..

I also tried to write like this:

"ON DUPLICATE KEY UPDATE status_type = status_type, startdate = startdate,ut = ut, name = name, value_home = value_home, value_away = value_away ";

but that didn't work - there was no update, but instead it seems a new row was created and deleted. So how should the correct query look like?

I found a solution that worked here: stackoverflow.com/questions/22699598/prepared-statement-with-on-duplicate-key Each of the columns for the update is put within "VALUES()".

 $sql = "INSERT INTO wp_mytable "
   . "(status_type, startdate,ut ,name ,value_home ,value_away ,sport_name ,event_id ) "
   . "VALUES (%s,%s,%s,%s,%s,%s,%s,%s) "
   . "ON DUPLICATE KEY UPDATE status_type = VALUES(status_type), sport_name=VALUES(sport_name), "
   . "startdate = VALUES(startdate),ut = VALUES(ut), name = VALUES(name), "
   . "value_home = VALUES(value_home), value_away = VALUES(value_away)";

    $sql = $wpdb->prepare($sql,$status_type,$startdate,$ut ,$name ,$value_home ,$value_away, $sport_name, $event_id );