desktop application connection string

namespace Payroll
{
    class Connection
    {
        private  static SqlConnection SqlCon;

        //private readonly static SqlConnection SqlCon = new SqlConnection("Server=petunia.arvixe.com; database=visiondb; uid=vision1; password=vision2;");

        public static SqlConnection CON
        {
            get
            {
              return   SqlCon = new SqlConnection("Server=WIN-PC\\SQLEXPRESS; database=Payroll;integrated Security=SSPI");
            }
        }
    }
}