Question

I’m trying to stop the user from entering the same string value for the “title” field in an appointment creation app in a calendar, as homework.

Here is what I thought of so far:

private static String[] CHECK = {TITLE};
    private Cursor addAppointment(String title, String time, String details){
        calendarData = new CalendarData(this);
        SQLiteDatabase db1 = calendarData.getReadableDatabase();
        SQLiteDatabase db = calendarData.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(DATE, calendar.getDate());
        values.put(TITLE, title);
        values.put(TIME, time);     
        values.put(DETAILS, details);
        db.insertOrThrow(TABLE_NAME, null, values);
        Cursor titleCursor = db1.query(TABLE_NAME, CHECK, TITLE+" = "+appointmentTitle.getText().toString(), null, null, null, null);
        if(titleCursor.getString(0) != null){//MEANING THERE IS A DUPLICATE
            final AlertDialog alertDialog = new AlertDialog.Builder(this).create();
            alertDialog.setMessage("You've entered a duplicate title field, please rename.");
            alertDialog.setButton("OK", new DialogInterface.OnClickListener() {
                  public void onClick(DialogInterface dialog, int which) {

                   alertDialog.dismiss();

                } });
            alertDialog.show();
        }
        return titleCursor;
    }

But I don’t like the idea of having everything in my addAppointments method, I’d rather leave it clean and simple.

I tried doing the following as an alternative:

private static String[] CHECK = {TITLE};
    private void addAppointment(String title, String time, String details){
        calendarData = new CalendarData(this);
        SQLiteDatabase db1 = calendarData.getReadableDatabase();
        SQLiteDatabase db = calendarData.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(DATE, calendar.getDate());
        values.put(TITLE, title);
        values.put(TIME, time);     
        values.put(DETAILS, details);
        db.insertOrThrow(TABLE_NAME, null, values);
    }

    private Cursor checkTitle(){
        calendarData = new CalendarData(this);
        SQLiteDatabase db1 = calendarData.getReadableDatabase();

        Cursor titleCursor = db1.query(TABLE_NAME, CHECK, TITLE+" = "+appointmentTitle.getText().toString(), null, null, null, null);

        startManagingCursor(titleCursor);
        return titleCursor;
    }

    private void showTitleError(Cursor cursor){
        if(cursor.getString(0) != null){//MEANING THERE IS A DUPLICATE
            final AlertDialog alertDialog = new AlertDialog.Builder(this).create();
            alertDialog.setMessage("You've entered a duplicate title field, please rename.");
            alertDialog.setButton("OK", new DialogInterface.OnClickListener() {
                  public void onClick(DialogInterface dialog, int which) {

                   alertDialog.dismiss();

                } });
            alertDialog.show();
        }
    }

but I get this error in both cases: 04-24 17:56:51.263: E/AndroidRuntime(17856): android.database.sqlite.SQLiteException: no such column: hello: , while compiling: SELECT title FROM appointments WHERE title = hello

Please if you have any advice please share, thank you.

Answer 1

You need to wrap appointmentTitle.getText().toString() in single quotes:

db1.query(TABLE_NAME, CHECK, TITLE+" = '"+appointmentTitle.getText().toString() + "'", null, null, null, null);

That way your assembled query looks like:

SELECT title FROM appointments WHERE title = 'hello'

As other posters have courteously noted, however, this can cause an SQL injection issue if your query here takes User input. Adapting to a parameterized approach is the better way.