public function sum($table, $field, $conditions = false)
    {
        return $this->executeAggregate('SUM', $table, $field, $conditions);
    }
public function sum($table, $field, $conditions = false)
    {
        return $this->executeAggregate('SUM', $table, $field, $conditions);
    }
public function sum ( $ table , $ field , $ conditions = false ) { return $ this -> executeAggregate ( 'SUM' , $ table , $ field , $ conditions ) ; }
Returns the sum of specified table field and conditions

@param string $table
@param string $field
@param mixed $conditions
@return float
Returns the sum of specified table field and conditions