/// <summary>
        /// Returns a <see cref="System.String"/> that represents this instance.
        /// </summary>
        /// <returns>
        /// A <see cref="System.String"/> that represents this instance.
        /// </returns>
        public override string ToString()
        {
            var sb = new StringBuilder();

            // Base operator
            sb.Append("CALL ");
            sb.Append(Procedure);
            sb.Append("(");

            // Columns
            var values = ValueCollection.GetValues();

            if (values != null && values.Length > 0)
            {
                foreach (var v in values)
                {
                    sb.Append(v);
                    sb.Append(",");
                }

                sb.Length--;
            }

            sb.Append(")");

            return(sb.ToString());
        }