C# 如何获取可执行文件路径的上上级目录

DirectoryInfo di = new DirectoryInfo(string.Format(@"{0}..\..\", Application.StartupPath));
di.FullName 就是你想要的
..\有几个就是往回退几层

 public SQLiteConnection conn;      
        //public string connstr = "Data Source = C:\\Users\\wuchao\\source\\repos\\SAW-1000\\SAW-1000\\Modle\\db\\ssbio.db;Version=3;";
        public DirectoryInfo di = new DirectoryInfo(string.Format(@"{0}..\..\..\", Application.StartupPath));
        public string connstr = "";

        //打开数据库
        public void Open()
        {
            try
            {
                connstr = "Data Source =" + di.FullName + @"Modle\db\ssbio.db";
                conn = new SQLiteConnection(connstr);
                conn.Open();
            }
            catch (Exception)
            {
                throw new Exception("打开数据库失败");
            }         
        }