1. Cosc 5/4730 Android and Blackberry SQLite

2. For the sql language syntax, please see SQlite documentation – http://www.sqlite.org http://www.sqlite.org Both Android and Blackberry implement the SQLite package – But very differently.

3. BLACKBERRY SQLite

4. Blackberry SQLite net.rim.device.api.database.* – accessible only by signed applications For the purposes of the class, you don’t need a signing keys. But if you plan to use an on the phone. » Category: Signed: This element is only accessible by signed applications. If you intend to use this element, please visit http://www.blackberry.com/go/codesigning to obtain a set of code signing keys. Code signing is only required for applications running on BlackBerry smartphoneshttp://www.blackberry.com/go/codesigning – development on BlackBerry Smartphone Simulators can occur without code signing.

5. SQLite Database files Each SQLite® database is stored in a single file. – If you only specify the database name as the parameter value to DatabaseFactory.create(), the database file is created on the SD card of the device. – The default location for the database file is /SDCard/databases/ /. The name of the application that creates the database is included in the path to avoid name collisions.

6. Opening/create a DB Uses DatabaseFactory – open() //opens db, throws exception if fails – create() //creates db, but if fails throws exception – examples: Database d; //using default location on the SDcard d = DatabaseFactory.create("myDB.db"); d = DatabaseFactory.open("myDB.db");

7. Opening/create a DB Throws the following exceptions DatabasePathException – Bad path or SDCard not there. OS 5 Storm and Bold and 6+ can use internal ControlledAccessException – on access restriction DatabaseIOException – Can’t open it generally.

8. Statement interface 1.Creation: Statement = Database.createStatement(String) 2.Preparation: via Statement.prepare() 3.Bind: of any formal parameters in the statement to actuals via Statement.bind(int, int) and associated methods, starting from 1 for the first formal. 4.Query Execution: via Statement.getCursor(), which returns a Cursor 5.Update Execution: via Statement.execute()

9. Statements and cursor Use the statement, we then use SQLite sql statements to work on the database. For select statements, it returns a cursor From the cursors, we get Row object for each row of data selected.

10. example Create Db and add a data d = DatabaseFactory.create("myDB.db"); Statement st; st = d.createStatement( "CREATE TABLE 'HighScore' ('Name' TEXT, 'Score' INTEGER )" ); st.prepare(); st.execute(); st.close(); //add some data st = d.createStatement("INSERT INTO HighScore(Name,Score) VALUES ('Jim',3012)"); st.prepare(); st.execute(); st.close();

11. Example (2) Read back the data st = d.createStatement("SELECT Name,Score FROM HighScore"); st.prepare(); net.rim.device.api.database.Cursor c = st.getCursor(); Row r; while(c.next()) { r = c.getRow(); System.out.println("Row "+i+ "is "+r.getString(0)+" "+r.getInteger(1)); } c.close(); st.close() Where 0 is Name and 1 is Score column.

12. Closing the database Don’t forget to close the database when you are done. try { d.close(); //where d is the database. } catch (DatabaseIOException e) { //for some reason the db can’t be closed. }

13. finally Don’t forgot to close everything – Cursor, statements and database – It releases all the resources that they are holding. Some more code samples on-line : – http://docs.blackberry.com/en/developers/deliver ables/8682/Create_a_SQLite_database_761831_1 1.jsp http://docs.blackberry.com/en/developers/deliver ables/8682/Create_a_SQLite_database_761831_1 1.jsp

14. A Note There is a RecordStore that can be used instead of SQLite – works on the rest of the phones – Also, not a signed API either.

15. ANDROID SQLite

16. SQLite and Android The similarity ends at the name between blackberry and android. – It SQLite, but handled very differently. Package – android.database.sqlite Normally the SQLite is implemented in a separate class from the Activity class.

17. SQL language Android sqlite uses sql, but the methods may break up the statement – example String WhereClause and String[] WhereArgs sql and android query examples – select Name, Score from HighScore where name=‘jim’; db.query(true, DATABASE_TABLE, new String[] {KEY_NAME, KEY_SCORE, }, KEY_NAME + "=\'" + VarName+"\'",, null, null, null, null, null); – NOTE the single quotes, which are required for any Text (android term), varchar, or string fields in the table – Select Name,Score from HighScore; db.query(true, DATABASE_TABLE, new String[] {KEY_NAME, KEY_SCORE}, null, null, null, null, null, null); – The red null so there is no WHERE CLAUSE.

18. DB class First you need to create a class to handle the database. – In my case, DBAdapter. I'm also using a number of constants to simplify typing errors let the compiler find my typing errors. public class DBAdapter { public static final String KEY_NAME = "Name"; public static final String KEY_SCORE = "Score"; private static final String TAG = "DBAdapter"; private static final String DATABASE_NAME = "myDB"; private static final String DATABASE_TABLE = "HighScore"; private static final int DATABASE_VERSION = 1; private static final String DATABASE_CREATE = "CREATE TABLE HighScore (Name TEXT, Score INTEGER );"; private final Context context; private DatabaseHelper DBHelper; private SQLiteDatabase db; public DBAdapter(Context ctx) { this.context = ctx; DBHelper = new DatabaseHelper(context); }

19. Extend SQLiteOpenHelper A helper class to manage database creation and version management. – You create a subclass implementing onCreate(SQLiteDatabase), onUpgrade(SQLiteDatabase, int, int) and optionally onOpen(SQLiteDatabase) – This class takes care of opening the database if it exists, creating it if it does not, and upgrading it as necessary. – Transactions are used to make sure the database is always in a sensible state.

20. DB class (2) subclass in DBAdapter private static class DatabaseHelper extends SQLiteOpenHelper { DatabaseHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); } @Override public void onCreate(SQLiteDatabase db) { //only called when the database is created! db.execSQL(DATABASE_CREATE); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE); onCreate(db); }

21. Now our stuff Add a few classes in DBAdapter to do the heavy lifting. // ---opens the database--- public DBAdapter open() throws SQLException { db = DBHelper.getWritableDatabase(); return this; } // ---closes the database--- public void close() { DBHelper.close(); db.close(); }

22. SQLiteDatabase methods Some of the common methods – void execSQL(String sql) Execute a single SQL statement that is not a query. – long insert(String table, String nullColumnHack, ContentValues values) method for inserting a row into the database. – long insertOrThrow(String table, String nullColumnHack, ContentValues values) method for inserting a row into the database or throws a SQLException – Cursor query(String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy) Query the given table, returning a Cursor over the result set. There are several query methods that can be used.

23. SQLiteDatabase methods (2) – int delete(String table, String whereClause, String[] whereArgs) method for deleting rows in the database. – public Cursor rawQuery (String sql, String[] selectionArgs) Runs the provided SQL and returns a Cursor over the result set. Sql is the SQL query. The SQL string must not be ; terminated selectionArgs You may include ?s in where clause in the query, which will be replaced by the values from selectionArgs. The values will be bound as Strings. – Maybe null.

24. Now our stuff (2) // ---insert into the database--- public long insertName(String name, Integer value) { ContentValues initialValues = new ContentValues(); initialValues.put(KEY_NAME, name); initialValues.put(KEY_SCORE, value); return db.insert(DATABASE_TABLE, null, initialValues); } // ---retrieves all rows--- public Cursor getNames() { Cursor c = db.query(DATABASE_TABLE, new String[] {KEY_NAME, KEY_SCORE}, null, null, null, null, KEY_NAME); if (c != null ) //make sure db is not empty! c.moveToFirst(); return c; }

25. Now our stuff (3) public Cursor getRow(long rowId) throws SQLException { Cursor mCursor = db.query(true, DATABASE_TABLE, new String[] { KEY_ROWID, KEY_NAME, KEY_IP, KEY_OWNER }, KEY_ROWID + "="+ rowId, null, null, null, null, null); if (mCursor != null) { mCursor.moveToFirst(); } return mCursor; } // ---updates a row--- public boolean updateRow(String name, int score) { ContentValues args = new ContentValues(); args.put(KEY_SCORE, score); //returns true if one or more updates happened, otherwise false. return db.update(DATABASE_TABLE, args, KEY_NAME + "= \'" + name+"\'", null) > 0; }

26. Now our stuff (4) // ---deletes a particular row--- public boolean deleteRow(long rowId) { return db.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0; } //Delete all rows with name public boolean deleteName(String name) { return db.delete(DATABASE_TABLE, KEY_NAME + "= \'" + name+"\'", null) > 0; }

27. The Activity class. create an activity class and add DBAdatper db = new DBAdapter(this); Access and use the DB. db.open(); id = db.insertName("Jim", 3012); note if (id == -1) then it failed to insert //whatever else you want to do. db.close();

28. Cursor notes The queries all return Cursor, so you need to pull the information out of it. – In my example, there are 2 columns in the db (and both are requested) Cursor c = db.getNames(); String str = “Name: " + c.getString(0); //name str += " Score:" + c.getInt(1); //score

29. Cursor notes (2) The Score column is actually an integer, so I could use.getInt(1) as well. Cursor has a number of useful methods double getDouble(int columnIndex), float getFloat(int columnIndex), int getInt(int columnIndex), long getLong(int columnIndex), short getShort(int columnIndex), String getString(int columnIndex) String[] getColumnNames() – Returns a string array holding the names of all of the columns in the result set in the order in which they were listed in the result. int getCount() – Returns the numbers of rows in the cursor. int getColumnCount() – Return total number of columns

30. Example with Cursor public void delRowbyName(String name) { db.open(); Cursor c = db.getNames(); for(c.moveToFirst(); !c.isAfterLast(); c.moveToNext()) { //0 name, 1 score label1.setText(c.getString(0) + " " + c.getInt(1)); } db.close(); }

31. Debugging a "stopped unexpectedly" bring up the ddms – ddms.bat or eclipse ddms – There will you give a way to debug your app, including what caused – Check the log for Errors (in red)

32. debugging the database The system stores databases in the /data/data/package_name/databases folder by default. In a command line using the adb (Android Debug Bridge - found in the android sdk tools library) you can access the databases on a running emulator like below – adb -s emulator-5554 shell assuming 5554 is your emulator – sqlite3 /data/data/package_name/databases/database_name After this you can type normal SQL commands to test the content. For example: – SELECT * FROM table_name; The output format is pretty ugly, but workable.

33. References Creating an using Databases with android – http://www.devx.com/wireless/Article/40842 Android Tutorials – http://www.helloandroid.com/tutorials – http://www.helloandroid.com/ Some good general help Android developer site – http://developer.android.com/intl/zh- CN/reference/android/database/sqlite/package- summary.html

34. Q A &