Android - DBHelper

Android using Sqlite as primary storage for android application, below is the sample code for create, upgrade or delete database.


Usually you will require to create one Helper for 1 database, we create our first helper class name "DBHelper", this class extends SQLiteOpenHelper and you need implement at least 2 methods

• onCreate()
• onUpgrade()

Always create only single instance for any DBHelper to avoid open & close connection of DB.

   public static DBHelper getInstance() {

        if(instance == null) {

            instance = new UserDatabaseHelper();

        }

        return instance;

    }

After install and start the app, verify if the db created.

root@android:/data/data/com.androidtutorial/databases # ls

Songs.db

Songs.db-journal

e3 Songs.db                                                                   <

SQLite version 3.7.16 2013-03-18 11:39:23 [www.ptsoft.org] [www.ptdave.com]

Enter ".help" for instructions

Enter SQL statements terminated with a ";"

sqlite> .tables

Songs             android_metadata

sqlite> select * from Songs;

sqlite> select * from Songs;

song1

sqlite> 

The songs.db is created.

One confusing about onUpgrade, if you upgrade the db version from 2~10, don't expect onUpgrade will handle for you, you need do some checking as below.

   @Override

    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

        Log.d(TAG, "onUpgrade ..." + oldVersion ); 

        oldVersion += 1;

        if(oldVersion < newVersion) {

            onUpgrade(db, oldVersion, newVersion);

        }

    }

Source code - https://www.dropbox.com/s/1otqfo60bjd1qba/AndroidTutorial.tgz