Question

I also want to take off the string after that till the next comma, and if that string is after “select” then I want to replace anything after select and till the next comma.
For example:
select a.column, a.myID, a.studentID from mytable

I have many textfiles like this so I need something that takes care of it like if I want to replace column with empty string it should look like after replace
select a.myID, a.studentID from mytable

and If I want to replace myID with empty string it should look like this after replace
select a.column, a.studentID from mytable

and If i want to replace studentID with empty string it should look like this
select a.column, a.myID from mytable.

Thanks
I’m working in C# I was thinking of using regex but can’t come up with a regex.

Answer 1

This is what you need >>

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);
  }
}

Test this code here.