public void FixNull()
    {
        if (NullFlag == -1 && _dbValue.IsDBNull())
        {
            switch (DbDataType)
            {
            case DbDataType.Char:
            case DbDataType.VarChar:
                DbValue.SetValue(string.Empty);
                break;

            case DbDataType.Guid:
                DbValue.SetValue(Guid.Empty);
                break;

            case DbDataType.SmallInt:
                DbValue.SetValue((short)0);
                break;

            case DbDataType.Integer:
                DbValue.SetValue((int)0);
                break;

            case DbDataType.BigInt:
            case DbDataType.Binary:
            case DbDataType.Array:
            case DbDataType.Text:
                DbValue.SetValue((long)0);
                break;

            case DbDataType.Numeric:
            case DbDataType.Decimal:
                DbValue.SetValue((decimal)0);
                break;

            case DbDataType.Float:
                DbValue.SetValue((float)0);
                break;

            case DbDataType.Double:
                DbValue.SetValue((double)0);
                break;

            case DbDataType.Date:
            case DbDataType.TimeStamp:
                DbValue.SetValue(DateTime2.UnixEpoch);
                break;

            case DbDataType.Time:
                DbValue.SetValue(TimeSpan.Zero);
                break;

            case DbDataType.Boolean:
                DbValue.SetValue(false);
                break;

            case DbDataType.TimeStampTZ:
            case DbDataType.TimeStampTZEx:
                DbValue.SetValue(new FbZonedDateTime(DateTime2.UnixEpoch, TimeZoneMapping.DefaultTimeZoneName));
                break;

            case DbDataType.TimeTZ:
            case DbDataType.TimeTZEx:
                DbValue.SetValue(new FbZonedTime(TimeSpan.Zero, TimeZoneMapping.DefaultTimeZoneName));
                break;

            case DbDataType.Dec16:
            case DbDataType.Dec34:
                DbValue.SetValue(new FbDecFloat(0, 0));
                break;

            case DbDataType.Int128:
                DbValue.SetValue((BigInteger)0);
                break;

            default:
                throw IscException.ForStrParam($"Unknown sql data type: {DataType}.");
            }
        }
    }