SQLiteException - only happens on some devices

I recently published an app to the market place. From the developers console it seems about 1-2% of my users are having this issue. 1-2% is small but people are more inclined to leave comments when something doesn't work rather than when it does which could negatively effect downloads.

Unfortunately the developers console only lists the platform as 'other', but my app is available to those with SDK 1.6+. I'm also unable to recreate this issue and no user has contacted me directly so I'm unable to get any more information about the devices it fails on.

Here is the stack

android.database.sqlite.SQLiteException: no such table: QUESTIONS: , while compiling: SELECT * FROM QUESTIONS WHERE DIFFICULTY=2 ORDER BY RANDOM() LIMIT 20
at android.database.sqlite.SQLiteCompiledSql.native_compile(Native Method)
at android.database.sqlite.SQLiteCompiledSql.compile(SQLiteCompiledSql.java:91)
at android.database.sqlite.SQLiteCompiledSql.<init>(SQLiteCompiledSql.java:64)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:80)
at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:46)
at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:53)
at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1434)
at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1404)
at com.app.myapp.db.DBHelper.getQuestionSet(DBHelper.java:140)
at com.app.myapp.SplashActivity.getQuestionSetFromDb(SplashActivity.java:109)
at com.app.myapp.SplashActivity.onClick(SplashActivity.java:58)
at android.view.View.performClick(View.java:2421)
at android.view.View$PerformClick.run(View.java:8867)
at android.os.Handler.handleCallback(Handler.java:587)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:143)
at android.app.ActivityThread.main(ActivityThread.java:5068)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.j开发者_如何学Goava:521)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:858)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
at dalvik.system.NativeStart.main(Native Method)

getQuestionSetFromDb(SplashActivity.java:109) refers to

List<Question> questions = myDbHelper.getQuestionSet(diff, numQuestions);

Which refers to

public List<Question> getQuestionSet(int difficulty, int numQ){
    List<Question> questionSet = new ArrayList<Question>();
    Cursor c = myDataBase.rawQuery("SELECT * FROM QUESTIONS WHERE DIFFICULTY=" + difficulty +
            " ORDER BY RANDOM() LIMIT " + numQ, null);
    while (c.moveToNext()){
        //Log.d("QUESTION", "Question Found in DB: " + c.getString(1));
        Question q = new Question();
        q.setQuestion(c.getString(1));
        q.setAnswer(c.getString(2));
        q.setOption1(c.getString(3));
        q.setOption2(c.getString(4));
        q.setOption3(c.getString(5));
        q.setRating(difficulty);
        questionSet.add(q);
    }
    return questionSet;
}

}

Does anyone know of a probable cause? It's strange this is only happening with a small amount of installs and being unable to determine the SDK level/device they are using makes it more difficult.

Any help is appreciated

EDIT: Due to the responses I'm including how the db is created.

First, my activity has this (this is the same method which causes the crash)

    private List<Question> getQuestionSetFromDb() throws Error {
    int diff = getDifficultySettings();
    int numQuestions = getNumQuestions();
    DBHelper myDbHelper = new DBHelper(this);
    try {
        myDbHelper.createDataBase();
    } catch (IOException ioe) {
        throw new Error("Unable to create database");
    }
    try {
        myDbHelper.openDataBase();
    }catch(SQLException sqle){
        throw sqle;
    }
    List<Question> questions = myDbHelper.getQuestionSet(diff, numQuestions);
    myDbHelper.close();
    return questions;
}

myDBhelper.createdatabase() calls

public void createDataBase() throws IOException{

    boolean dbExist = checkDataBase();
    if(!dbExist)
    {
        //By calling this method and empty database will be created into the default system path
        //of your application so we are gonna be able to overwrite that database with our database.
        this.getReadableDatabase();

        try {
            copyDataBase(); 
        } catch (IOException e) {
            throw new Error("Error copying database");
        }
    }
}

checkDatabase()

    private boolean checkDataBase(){
    SQLiteDatabase checkDB = null;
    try{
        String myPath = DB_PATH + DB_NAME;
        checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
    }catch(SQLiteException e){
        //database does't exist yet.
    }
    if(checkDB != null){
        checkDB.close();
    }

    return checkDB != null ? true : false;
}

copyDatabase()

    private void copyDataBase() throws IOException{

    //Open your local db as the input stream
    InputStream myInput = myContext.getAssets().open(DB_NAME);

    // Path to the just created empty db
    String outFileName = DB_PATH + DB_NAME;

    //Open the empty db as the output stream
    OutputStream myOutput = new FileOutputStream(outFileName);

    //transfer bytes from the inputfile to the outputfile
    byte[] buffer = new byte[1024];
    int length;
    while ((length = myInput.read(buffer))>0){
        myOutput.write(buffer, 0, length);
    }

    //Close the streams
    myOutput.flush();
    myOutput.close();
    myInput.close();

}

Variables

    private static String DB_PATH = "/data/data/com.app.myapp/databases/";
private static String DB_NAME = "questionsDb";
private SQLiteDatabase myDataBase; 
private final Context myContext;

Apoligies, I really should have included this initially

The error reports about a missing "QUESTIONS" database. DB_NAME is "questionsDb".

The int difficulty, appended with + to a string, puzzles me too (was already reported from another user earlier in this thread).

I just feel the way you are creating the database is causing the problem. There is nothing wrong with it; as you said it works on 98% of the devices.

In my opinion, you are probably better off extending SQLiteOpenHelper. This takes care of creating your database if it doesn't exist and you don't have to do any checks manually that you do.