Sql.SqlItem.this C# (CSharp) Method

        public string this[int x]
        {
            get
            {
                if (x < 0 || x >= _pos)
                    throw new IndexOutOfRangeException("x is out of range. Should be in rage of 0 and " + _pos + ", but its " + x);

                object obj = _values[x];
                if (obj == null)
                    throw new ArgumentNullException("obj");

                string str = obj.ToString();
                if ((obj is char) || (obj is string) || (obj is float) || (obj is double))
                    return string.Format("{0}{1}{0}", @"'", str);

                return str;
            }
        }