using System;

using System.Text.RegularExpressions;

​

public class Program

{

    public static void Main()

    {

      string testString = "\"effective_business_date\": \"${SQL_FILE=polarlake/parameter_polarlake_cob.sql}\", \"effective_business_date2\": \"${SQL_FILE=polarlake2/parameter_polarlake_cob2.sql}\", ";

            Regex regex = new Regex("\\${SQL_FILE=.+?}");

            string cleanString = regex.Replace(testString, a => PerformSqlOverrides(a.Groups[0].ToString()));

            Console.WriteLine(cleanString);

    }

    private static int i = 1;

    private static string PerformSqlOverrides(string asdasd) {

        return asdasd + "MAGIC-" + i++; 

    }

}