Cursor c=db.rawQuery("SELECT * FROM user", null);
            if(c.getCount()==0)
            {
                showMessage("Error", "No records found");
                return;
            }
            StringBuilder buffer=new StringBuilder();
            while(c.moveToNext())
            {
                buffer.append("Username:").append(c.getString(0)).append("n");
                buffer.append("Password:").append(c.getString(1)).append("n");
            }
            showMessage("Student Details", buffer.toString());