public static string Coalesce(this DataRow row, string fields)
        {
            if (row == null)
                throw new ArgumentNullException("row");

            return Coalesce(row.Table, fields);
        }

        public static string Coalesce(this DataTable dt, string fields)
        {
            if (dt == null)
                throw new ArgumentNullException("dt");

            if (string.IsNullOrWhiteSpace(fields))
                throw new ArgumentNullException("fields");

            var columns = fields.Split(';');

            foreach (var column in columns)
            {
                if (dt.Columns.Contains(column))
                    return column;
                if (DtEvaluator.FieldIsNull(column))
                    return DtEvaluator.FieldNull;
            }

            throw new KeyNotFoundException(string.Format("В таблице \"{0}\" отсутствуют поля \"{1}\"", dt.TableName, fields));
        }