final public function decrementColumnByPk($pk, $column, $step = 1, $table = null)
    {
        return $this->db->decrement($this->getTable($table), $column, $step)
                        ->whereEquals($this->getPk(), $pk)
                        ->execute();
    }
final public function decrementColumnByPk($pk, $column, $step = 1, $table = null)
    {
        return $this->db->decrement($this->getTable($table), $column, $step)
                        ->whereEquals($this->getPk(), $pk)
                        ->execute();
    }
final public function decrementColumnByPk ( $ pk , $ column , $ step = 1 , $ table = null ) { return $ this -> db -> decrement ( $ this -> getTable ( $ table ) , $ column , $ step ) -> whereEquals ( $ this -> getPk ( ) , $ pk ) -> execute ( ) ; }
Decrements column's value by associated PK's value

@param string $pk PK's value
@param string $column Target column
@param integer $step
@param string $table Optionally current table can be overridden
@return boolean
Decrements column s value by associated PK s value