using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(GenerateWhereClause("1", "2", "3"));

    }

    private static string GenerateWhereClause(params string[] clauses)

    {

        return clauses.JoinAsString(" AND ");

    }

}

​

public static class Extensions

{

    public static string JoinAsString(this IEnumerable<object> current, string separator)

    {

        var arr = current.Select(x => x.ToString()).ToArray();

        return string.Join(separator, arr);

    }

}