using System;
using System.Text.RegularExpressions;
 
class Program
{
  static void Main()
  {
    string input = "select ceiling(a.interest) as interest, a.myID as mID, a.studentID as sID from mytable";
    string column = "a.myID";
    string pattern = "((?<=\\bselect)\\s+[^,]*\\b" + Regex.Escape(column) + "\\b[^,]*\\s*,?|\\s*,\\s*[^,]*\\b" + Regex.Escape(column) + "\\b[^,]*(?=(?:,|\\sfrom\\b)))";
    string output = Regex.Replace(input, pattern, "", RegexOptions.IgnoreCase);
    Console.WriteLine(output);
  }
}