using System;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;

public class Program
{
    const string kvPair   = @"(?<pair>(?<key>.*?)\s*=\s*(?<value>.*?))";
    const string kvpRegex = "^" + kvPair + "$";
    const string csRegex  = @"^\s*(?<cs>(?:" + kvPair + @"\s*(;\s*|\s*$))+)$";

    public static void Main(string[] args)
    {
        const string input = @"Data Source=Instance1;User ID=;Initial Catalog=DB;Provider=SQLOLEDB.1;Integrated Security=SSPI;Auto Translate=False;";

        var match = Regex.Match(input, csRegex);
        Console.WriteLine("======\nSuccess: {0}\n======", match.Success);

        // 'smart' dictionary from the subcaptures:
        var dict = match.Groups["pair"]
            .Captures
            .Cast<Capture>()
            .Select(cap => Regex.Match(cap.Value, kvpRegex))
            .ToDictionary(submatch => submatch.Groups["key"].Value,
                          submatch => submatch.Groups["value"].Value);

        foreach (var kvp in dict)
            Console.WriteLine(kvp);

        // Getting just the DB1:
        Console.WriteLine("======\nCatalog: {0}\n======", dict["Initial Catalog"]);

        // raw access from csRegex full match:
        foreach (Capture cap in match.Groups["key"].Captures)
            Console.WriteLine("Key: '{0}'", cap.Value);
        foreach (Capture cap in match.Groups["value"].Captures)
            Console.WriteLine("Value: '{0}'", cap.Value);

        Console.WriteLine("======\nConnection string: '{0}'", match.Groups["cs"].Value);
    }
}