Android SQLite - Primary Key - Inserting into table

Question

Im in my final stages of creating a database for my android app, however, I cannot seem to get my primary key to increment. Here is my code where I set it up,

public class DatabaseHandler extends SQLiteOpenHelper {

    // All Static variables
    // Database Version
    private static final int DATABASE_VERSION = 17;

    // Database Name
    private static final String DATABASE_NAME = "journeyManager";

    // Contacts table name
    public static final String TABLE_JOURNEY = "journey";

    // Contacts Table Columns names
    private static final String KEY_P = "key";
    private static final String KEY_ID = "id";
    private static final String KEY_DIST = "distance";
    private static final String KEY_MPG = "mpg";
    private static final String KEY_COST = "cost";

    public DatabaseHandler(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    // Creating Tables
    @Override
    public void onCreate(SQLiteDatabase db) {
        String CREATE_JOURNEY_TABLE = "CREATE TABLE " + TABLE_JOURNEY + "("
                + KEY_P + " INTEGER PRIMARY KEY," + KEY_ID + " TEXT," + KEY_DIST + " TEXT,"
                + KEY_MPG + " TEXT," + KEY_COST + " TEXT )";
        db.execSQL(CREATE_JOURNEY_TABLE);
    }

    // Upgrading database
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // Drop older table if existed
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_JOURNEY);

        // Create tables again
        onCreate(db);
    }

    /**
     * All CRUD(Create, Read, Update, Delete) Operations
     */

    // Adding new contact
    void addJourneyData(Journey journey) {
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(KEY_P, journey.getpKey());
        values.put(KEY_ID, journey.getId());
        values.put(KEY_DIST, journey.getDistance()); // Contact Name
        values.put(KEY_MPG, journey.getMpg()); // Contact Phone
        values.put(KEY_COST, journey.getCost()); // Contact Phone

        // Inserting Row
        db.insert(TABLE_JOURNEY, null, values);
        db.close(); // Closing database connection
    }

    // Getting single contact
    Journey getJourney(int id) {
        SQLiteDatabase db = this.getReadableDatabase();

        Cursor cursor = db.query(TABLE_JOURNEY, new String[] { KEY_P + KEY_ID + 
                KEY_DIST, KEY_MPG, KEY_COST }, KEY_P + "=?",
                new String[] { String.valueOf(id) }, null, null, null, null);
        if (cursor != null)
            cursor.moveToFirst();

        Journey journey = new Journey();
        journey.setPkey(Integer.parseInt(cursor.getString(0)));
        journey.setId(String.valueOf(cursor.getString(1)));
        journey.setMpg(String.valueOf(cursor.getString(2)));
        journey.setDistance(String.valueOf(cursor.getString(3)));
        journey.setCost(String.valueOf(cursor.getString(4)));
        // return contact
        return journey;
    }

    // Getting All Contacts
    public List<Journey> getAllJourneys() {
        List<Journey> journeyList = new ArrayList<Journey>();
        // Select All Query
        String selectQuery = "SELECT  * FROM " + TABLE_JOURNEY;

        SQLiteDatabase db = this.getWritableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);

        // looping through all rows and adding to list
        if (cursor.moveToFirst()) {
            do {
                Journey journey = new Journey();
                journey.setPkey(Integer.parseInt(cursor.getString(0)));
                journey.setId(String.valueOf(cursor.getString(1)));
                journey.setMpg(String.valueOf(cursor.getString(2)));
                journey.setDistance(String.valueOf(cursor.getString(3)));
                journey.setCost(String.valueOf(cursor.getString(4)));
                // Adding contact to list
                journeyList.add(journey);
            } while (cursor.moveToNext());
        }

        // return contact list
        return journeyList;
    } 
}

Here is where I add the details into a database from a button on another activity,

db.addJourneyData(new Journey(1,timeStamp, distanceLabel, mpgAnswer, pplAnswer));

I get to the point, where it will add the first one in, but from then on it will say the primary key is not unique - therefore it doesn't update the database.

Also, I want the data to be in descending order, to do this, I use DESC, but where shall I place this?

Any help would be appreciated,

Many thanks,

Solution 1

To make the database auto-generate the primary key for you, just don't specify it yourself. Remove this line from the insert code:

values.put(KEY_P, journey.getpKey());

You can capture the generated id from the return value of insert().

Also, I want the data to be in descending order, to do this, I use DESC, but where shall I place this?

Assuming this applies to getAllJourneys() where you do a rawQuery(), just add the ORDER BY directly in the SQL:

String selectQuery = "SELECT  * FROM " + TABLE_JOURNEY + " ORDER BY " + KEY_P + " DESC";

Solution 2

Go through the following steps

Modify your Creating Tables code like this

// Creating Tables
@Override
public void onCreate(SQLiteDatabase db) {
    String CREATE_JOURNEY_TABLE = "CREATE TABLE " + TABLE_JOURNEY + "("
            + KEY_P + " INTEGER PRIMARY KEY AUTOINCREMENT DEFAULT 1 ," + KEY_ID + " TEXT," + KEY_DIST + " TEXT,"
            + KEY_MPG + " TEXT," + KEY_COST + " TEXT )";
    db.execSQL(CREATE_JOURNEY_TABLE);
}

by using

INTEGER PRIMARY KEY AUTOINCREMENT DEFAULT 1 

you can start increment from 1

Then remove the following code

    values.put(KEY_P, journey.getpKey());