protected void QuoteDefaultValues(MyCatSchemaCollection schemaCollection)
        {
            if (schemaCollection == null)
            {
                return;
            }
            if (!schemaCollection.ContainsColumn("COLUMN_DEFAULT"))
            {
                return;
            }

            foreach (MyCatSchemaRow row in schemaCollection.Rows)
            {
                object defaultValue = row["COLUMN_DEFAULT"];
                if (MetaData.IsTextType(row["DATA_TYPE"].ToString()))
                {
                    row["COLUMN_DEFAULT"] = String.Format("{0}", defaultValue);
                }
            }
        }