SqlConnection med variable i connection stringen [C#]

string connectionSrting = "Data Source='" + test + "'; Initial Catalog=Account; User ID=sa; Password=Windows; Integrated Security=TRUE";

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Xml;
using System.Data.SqlClient;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Form2 form2 = new Form2();
            form2.ShowDialog();
        }
        
        
        private void button2_Click(object sender, EventArgs e)
        {
            XmlDocument xDoc = new XmlDocument();
            xDoc.Load("C:\\Users\\Max\\Desktop\\config.xml");

            string test = xDoc.SelectSingleNode("Config/InstanceName").InnerText;

            MessageBox.Show(test);

            string connectionSrting = "Data Source='" + test + "'; Initial Catalog=Account; User ID=sa; Password=Windows; Integrated Security=TRUE";

            SqlConnection myConnection = new SqlConnection(connectionSrting);

            myConnection.Open();
            MessageBox.Show("Connected!");
            myConnection.Close();
        }
    }
}