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SQLite. Command line sqlite3 The command line sqlite3 is not installed on all devices To install, get sqlite3 from web page, and $ adb push sqlite3 /sdcard/

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Presentation on theme: "SQLite. Command line sqlite3 The command line sqlite3 is not installed on all devices To install, get sqlite3 from web page, and $ adb push sqlite3 /sdcard/"— Presentation transcript:

1 SQLite

2 Command line sqlite3 The command line sqlite3 is not installed on all devices To install, get sqlite3 from web page, and $ adb push sqlite3 /sdcard/ $ adb shell $ su # mount -o remount,rw -t yaffs2 /dev/block/mtdblock3 /system # dd if=/sdcard/sqlite3 of=/system/bin/sqlite3 # chmod 4755 /system/bin/sqlite3 # mount -o remount,ro -t yaffs2 /dev/block/mtdblock3 /system

3 Found Things Record a thing (e.g., audio, picture, text, video, web link, etc.) at a location When someone is near the location, perhaps play the thing. Allow things that are played to be selected in a sophisticate way – Include various information about the things Cache things and get things from the web

4 Things database idtypefilenameFile state latlongRecorded date Recorded time authorscoreLast playedTag 1Tag 2 1pic1.jpeghere /2/20101:01stephan1005/3/2010treebird Look in database and get thing from nearby and that matched other criteria For now, we will just use near by lat and long

5 SQLite SQLite is a scaled down version of SQL Data is in tables with rows and columns Each row is a data entry. SQL allows data to be stored and retrieved Basic things (see – Create database – Create table in the database – Insert data into the table – Get data from table (or tables), via query – Theres other stuff, but this is enough for us

6 Create database and table SQLiteDatabase myDatabase; myDatabase = openOrCreateDatabase( /mnt/sdcard/things.db", SQLiteDatabase.CREATE_IF_NECESSARY, null); – Makes a database called things.db – If no path, then db is in /data/data/ /databases – here we use a specific path so we can examine the db at the command line – Is database already exists, it does not make it Make table – Must specify the column name and type (e.g., integer) – Also, there must be a primary column (a key) such that each entry in this column is unique One way to do this is to include a column that is an integer that autoincrements myDatabase.execSQL("CREATE TABLE IF NOT EXISTS things" + "( id INTEGER PRIMARY KEY AUTOINCREMENT," + " type VARCHAR(40), " + " filename VARCHAR(40), " + " lat INTEGER, " + " long INTEGER);"); Name of table Key is named id and is integer Type is audio, pic, tex, etc. Filename of the thing Location of the thing If IF NOT EXIST is missing, then this will crash if the table already exists

7 Try it Make function createDatabase Call createDatabase from onCreate Run adb Change to the databases directory ls Run sqlite3 things.db.dump

8 Add data long newId = myDatabase.insert("things", null, values); Name of table Set of pairs (column name, data for that column) Id of entry ContentValues values = new ContentValues(); values.put("type", "audio"); values.put("filename", "1.mp4"); values.put("lat"," "); values.put("long"," ");

9 Try it Make function insertData() ContentValues values = new ContentValues(); values.put("type", "audio"); values.put("filename", "1.mp4"); values.put("lat"," "); values.put("long"," "); long newId = myDatabase.insert("things", null, values); Log.d(SQLPlay,insert returned id +newId); Run adb sqllite3 things.db.dump

10 Add three buttons – Record – Stop – Play Allow record audio, location, internet, camera

11 Next filename We will save the recorded data with name id.mp4, where id is the id from the database So, to determine the filename, we need to get the next id Or, insert a partial row, get the id and update the row idtypefilenameFile state latlongRecorded date Recorded time authorscoreLast playedTag 1Tag 2 1audio1.mp4here /2/20101:01stephan1005/3/2010treebird 2audionullhere76245/3/20102:02stephan995/4/2010singsong idtypefilenameFile state latlongRecorded date Recorded time authorscoreLast playedTag 1Tag 2 1audio1.mp4here /2/20101:01stephan1005/3/2010treebird 2audio2.mp4here76245/3/20102:02stephan995/4/2010singsong

12 ContentValues values = new ContentValues(); values.put("type", "audio"); values.put("lat, ); values.put("long, ); long newId = myDatabase.insert("things", null, values); Log.d(SQLPlay","newId="+newId); String filename = newId+".mp4"; ContentValues values2 = new ContentValues(); values2.put("filename", Long.toString(newId)+".mp4"); String wheres[] = new String[1]; wheres[0] = Long.toString(newId); myDatabase.update("things", values2, "id=?", wheres); Make a new column with the filename empty (null) Make file name Make filename column (value pairs like insert) update

13 location From previous lectures on location Add class attribtues – LocationManager locationManager; – String provider; Make setUpLocation and call from onCreate, after createDatabase public void setUpLocation() { Criteria criteria = new Criteria(); criteria.setAccuracy(Criteria.ACCURACY_FINE); criteria.setPowerRequirement(Criteria.NO_REQUIREMENT); locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE); provider = locationManager.getBestProvider(criteria, true); Location location = locationManager.getLastKnownLocation(provider); String locInfo = String.format("Initial loc = (%f, (%f meters up)", location.getLatitude(), location.getLongitude(), location.getAltitude() ); Log.d("SQLPlay","starting loc: "+locInfo); } Get location

14 Location when not moving/indoors Get gps lock since last reboot. That way,.getLastKnownLocation doesnt crash Add a random number to location Location location = locationManager.getLastKnownLocation(provider); Random generator = new Random(); int random1 = generator.nextInt( ); int random2 = generator.nextInt( ); int latitude = (int)(location.getLatitude()*1E6+random1); int longitude = (int)(location.getLongitude()*1E6+random2); Put this into getNextfileName function rm things.db Run and make a few files. Dump database

15 Record sound From previous project, cut record sound and paste into recordSound function Cut and paste stopRecording into stopRecordingButton.onClick – Make buttons nice Run on device Make a few entries adb -d pull /data/data/com.SQLPlay/files c:\audio adb -d pull /data/data/com.SQLPlay/databases c:\audio

16 Play sound Get location (done) Get database entry that is nearest to current location – Android query – SQL SELECT

17 Table = things Columns: array of the columns to be returned – E.g., null, returns all columns – E.g., String columns[] = filename; returns the filename {selection selectionArgs} is also know as WHERE (in SQL, one types …. WHERE ~ {selection selectionArgs} – E.g., selection = type=?; String selectionArgs[] = {audio} – E.g., selection = lat

18 cursor Cursor is used to get the results, which might be emtpy or have several rows, where each row has one or more columns You can scroll through the cursor – Also, you should close the cursor when done – Perhaps use startManagingCursor(c); c.moveToFirst(); while (c.isAfterLast() == false) { String row = new String(); for (int i=0; i

19 Try it Make function playAudio and call this function from playButton.onClick Make function, getfilename In playAudio, call getFilename In getFilename, put Cursor c = myDatabase.query (things, null, null, null, null, null, null, null); c.moveToFirst(); while (c.isAfterLast() == false) { String row = new String(); for (int i=0; i

20 String selection = lat

21 nearest But how to get a nearest point? – I dont think it is possible with this type of query rawQuery – Same as SQLite queries. – Androids query is easy, but very limited. rawQuery gives the full power of SQLite – If you know SQL, then you may as well use rawQuery

22 SQL SELECT SELECT column_name(s) FROM table_name WHERE column_name operator value SELECT * FROM things WHERE lat < Try in sqlite3 In shell, # sqlite3 things.db SELECT * from things ….

23 Smallest lat – SELECT * FROM things WHERE lat in (SELECT min(lat) ) Nearest lat to SELECT * FROM things WHERE abs(lat ) in (SELECT min(abs(lat ) ) ); – Nearest to La, Lo SELECT * FROM things WHERE abs(lat - La)+abs(long - Lo) in (SELECT min(abs(lat - La)+abs(long - Lo) ) ); Dont forget spaces, -Lo is an invalid string is Lo<0

24 Back to code Cursor c = myDatabase.rawQuery(…); String la = latitude; String lo = longitude; String ex = abs(lat – la) + abs(long – lo); String Q = SELECT * FROM things WHERE + ex + IN ( SELECT min( + ex + ) FROM things) ; ; Cursor c = myDatabase.rawQuery(Q, []);

25 File name String Q = SELECT filename FROM things WHERE + ex + IN ( SELECT min( + ex + ) FROM things) ; ; Cursor c = myDatabase.rawQuery(Q, []); String filename = c.getString(0); Log.d(SQLPlay,filename:+filename); Return filename;

26 Try it in getFilename function Location location = locationManager.getLastKnownLocation(provider); Random generator = new Random(); int random1 = generator.nextInt( ); int random2 = generator.nextInt( ); int latitude = (int)(location.getLatitude()*1E6+random1); int longitude = (int)(location.getLongitude()*1E6+random2); String la = latitude; String lo = longitude; String ex = abs(lat – la) + abs(long – lo); String Q = SELECT filename FROM things WHERE + ex + IN ( SELECT min( + ex + ) FROM things) ; ; Cursor c = myDatabase.rawQuery(Q, []); String filename = c.getString(0); Log.d(SQLPlay,filename:+filename); return filename;

27 finally In play, paste code to play audio from previous lecture


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