Question

Hello Stackoverflowers!

I created a simple sqlite DB like so.

//event table name
private static final String TABLE_EVENTS = "events";

//event table columns names
private static final String KEY_ID = "id";
private static final String KEY_EVENT = "event";

@Override
public void onCreate(SQLiteDatabase db) 
{
//String to define our database
String CREATE_EVENT_TABLE = "CREATE TABLE " + TABLE_EVENTS + "("
+ KEY_ID + " INTEGER PRIMARY KEY," + KEY_EVENT + " TEXT" + ")";

//create our database
db.execSQL(CREATE_EVENT_TABLE);
}

Which I understand to be a table with an id column and an event column.

in the event column I am storing a JSONObject converted to a string which I would like to retrieve from the table in FIFO(First in First Out) order, so that if my application crashes I can send the JSONObjects that I have stored next time the app is opened.

I can insert to the table without a problem using:

public void addEvent(JSONObject event)
{
    //get our database so we can add to it
    SQLiteDatabase db = this.getWritableDatabase();

    //define content values to store our values
    ContentValues values = new ContentValues();

    //add our event to the ContentValues
    values.put(KEY_EVENT, event.toString());

    //insert a row
    db.insert(TABLE_EVENTS, null, values);

    //close the database connection
    db.close();
}

I am having trouble querying for a specific row or event and getting the event from the database as well as a good method to keep track the order in which the events were inserted, so that I can pull them out in a FIFO order.

Sample code is especially helpful seeing as when I try to query I am getting syntax errors, and am not very familiar with SQLite.

Any help is much appreciated! Thank you for your time.

Answer 1

Hello VinC the best approach is to auto increment id, which is your primary key so you can do it by,

String CREATE_EVENT_TABLE = "CREATE TABLE " + TABLE_EVENTS + "("
+ KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT," + KEY_EVENT + " TEXT" + ")";

Now you can query database with orderby Id in Ascending order

database.query("TABLE_EVENTS", new String[]{"KEY_EVENT"},null,null, null, null,"KEY_ID ASC");