Hi,
perhaps this could help :
//RECORD INSERTION IN FREE TABLE WITH "CODE AFTER STORE "
// Get a db connection.
$db = JFactory::getDbo();
// Create a new query object.
$query = $db->getQuery(true);
// Insert columns from my "free table"
$columns = array('team_id', 'player_id', 'season_id');
// Inserting values from my Form Values
$values = array($db->quote($fields['tra_equipe_bl']->value), $db->quote($fields['tra_id_val']->value), $db->quote($fields['tra_saison_bl']->value));
// Prepare the insert query in your custom table
$query
->insert($db->quoteName('#__bl_players_team'))
->columns($db->quoteName($columns))
->values(implode(',', $values));
// Set the query using our newly populated query object and execute it.
$db->setQuery($query);
$db->execute();
This is working for me.