public override string AddMathFce(string _columnNameLeft, string _columnNameRight, MathOperatorEnum _operator, bool _addParenthises)
        {
            string _retVal = "";

            switch (_operator)
            {
            case MathOperatorEnum.Plus:
                _retVal = "[" + _columnNameLeft + "] + [" + _columnNameRight + "]";
                break;

            case MathOperatorEnum.Minus:
                _retVal = "[" + _columnNameLeft + "] - [" + _columnNameRight + "]";
                break;

            case MathOperatorEnum.Multiple:
                _retVal = "[" + _columnNameLeft + "] * [" + _columnNameRight + "]";
                break;

            case MathOperatorEnum.Divide:
                _retVal = "[" + _columnNameLeft + "] / [" + _columnNameRight + "]";
                break;

            default:
                break;
            }

            if (_retVal.Length > 0)
            {
                if (_addParenthises)
                {
                    _retVal = "(" + _retVal + ")";
                }
            }
            return(_retVal);
        }