How to use sqlite in fragment

I cannot seem to find a tutorial anywhere that can help me use an sqlite db in a fragment. I am so frustrated as I re made the database and when I click on the save button it crashes. What do I have to do to get it to work?

public class Tab3 extends Fragment {

Button save, reset, load;
EditText logl, logd, logid;
DataHandler handler;


@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.tab_3, container, false);
    return v;


}

@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);

    save = (Button) getActivity().findViewById(R.id.buttonSave);
    load = (Button) getActivity().findViewById(R.id.buttonShow);
    reset = (Button) getActivity().findViewById(R.id.reset);
    logl = (EditText) getActivity().findViewById(R.id.logLength);
    logd = (EditText) getActivity().findViewById(R.id.logDiameter);
    logid = (EditText) getActivity().findViewById(R.id.logId);
    save.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            String getLoglength = logl.getText().toString();
            String getLogdiameter = logd.getText().toString();
            String getLogid = logid.getText().toString();
            handler = new DataHandler(getActivity());
            handler.open();
            long id = handler.insertData(getLoglength, getLogdiameter,getLogid);
            Toast.makeText(getActivity(), "Data Inserted", Toast.LENGTH_LONG).show();
            handler.close();
        }
    });

    load.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String getLoglength, getLogdiameter, getLogid;
            getLoglength = "";
            getLogdiameter = "";
            getLogid = "";
            handler = new DataHandler(getActivity());
            handler.open();
            Cursor C = handler.returnData();
            if (C.moveToFirst()){

            }
            do{
                getLoglength = C.getString(0);
                getLogdiameter = C.getString(1);
                getLogid = C.getString(2);

            }
            while (C.moveToNext());

            handler.close();
            Toast.makeText(getActivity(), "Log Length:" +getLoglength+ "Log Diameter:  " +getLogdiameter+ "Log ID:  " +getLogid, Toast.LENGTH_LONG).show();
        }
    });
}

}

This is my Datahandler

    public class DataHandler {


    public static final String LOGLENGTH = "logl";
    public static final String LOGDIAMETER = "logd";
    public static final String LOGID = "logid";
    public static final String TABLE_NAME = "mylogtable";
    public static final String DATABASE_NAME = "mydatabase";
    public static final int DATABASE_VERSION = 1;
    private static final String TABLE_CREATE = "CREATE TABLE "+TABLE_NAME+" (_id INTEGER PRIMARY KEY AUTOINCREMENT, "+LOGLENGTH+" VARCHAR(255), "+LOGDIAMETER+" VARCHAR(255), "+LOGID+" VARCHAR(255));";

    DatabaseHelper dbhelper;
    Context ctx;
    SQLiteDatabase db;

    public DataHandler(Context ctx) {
        this.ctx = ctx;
    }

    private static class DatabaseHelper extends SQLiteOpenHelper {

        public DatabaseHelper(Context ctx) {
            super(ctx, DATABASE_NAME, null, DATABASE_VERSION);
        }


        @Override
        public void onCreate(SQLiteDatabase db) {
            try {
                db.execSQL(TABLE_CREATE);
            } catch (SQLException e) {
                e.printStackTrace();
            }

        }


        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            db.execSQL("DROP TABLE IF EXISTS mylogtable");
            onCreate(db);
        }

    }

    public DataHandler open() {
        db = dbhelper.getWritableDatabase();
        return this;
    }

    public void close(){
        dbhelper.close();
    }

    public long insertData (String logl, String logd, String logid){
        ContentValues content = new ContentValues();
        content.put(LOGLENGTH, logl);
        content.put(LOGDIAMETER, logd);
        content.put(LOGID, logid);
        return db.insertOrThrow(TABLE_NAME, null, content);
    }

    public Cursor returnData(){
        return db.query(TABLE_NAME, new String[] {LOGID, LOGLENGTH, LOGDIAMETER}, null, null, null, null, null);
    }
}