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/

$ 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

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

Things databaseid type filename File

state lat long Recorded

dateRecorded time

author score Last played Tag 1 Tag 2

1 pic 1.jpeg here 75.. 36.. 5/2/2010 1:01 stephan 100 5/3/2010 tree bird

Look in database and get thing from nearby and that matched other criteria

For now, we will just use near by lat and long

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 http://www.w3schools.com/sql/default.asp

– Create database– Create table in the database– Insert data into the table– Get data from table (or tables), via query– There’s other stuff, but this is enough for us

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/<appname>/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 integerType 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

Try it

• Make function createDatabase• Call createDatabase from onCreate• Run adb• Change to the databases directory• ls• Run sqlite3 things.db “.dump”

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","75001200"); values.put("long","36000000");

Try it

• Make function insertData()

ContentValues values = new ContentValues(); values.put("type", "audio"); values.put("filename", "1.mp4"); values.put("lat","75001200"); values.put("long","36000000");long newId = myDatabase.insert("things", null, values);Log.d(“SQLPlay”,”insert returned id “+newId);

• Run• adb sqllite3 things.db “.dump”

• Add three buttons– Record– Stop– Play

• Allow record audio, location, internet, camera

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

id type filename File state

lat long Recorded date

Recorded time

author score Last played Tag 1 Tag 2

1 audio

1.mp4 here 75.. 36.. 5/2/2010 1:01 stephan 100 5/3/2010 tree bird

2 audio

null here 76 24 5/3/2010 2:02 stephan 99 5/4/2010 sing song

id type filename File state

lat long Recorded date

Recorded time

author score Last played Tag 1 Tag 2

1 audio

1.mp4 here 75.. 36.. 5/2/2010 1:01 stephan 100 5/3/2010 tree bird

2 audio

2.mp4 here 76 24 5/3/2010 2:02 stephan 99 5/4/2010 sing song

ContentValues values = new ContentValues(); values.put("type", "audio"); values.put("lat“, 36000000); values.put("long“,74000000); 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

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) @ (%f meters up)", location.getLatitude(), location.getLongitude(), location.getAltitude() ); Log.d("SQLPlay","starting loc: "+locInfo); }

Get location

Location when not moving/indoors• Get gps lock since last reboot. That way, .getLastKnownLocation

doesn’t crash• Add a random number to location Location location = locationManager.getLastKnownLocation(provider); Random generator = new Random(); int random1 = generator.nextInt( 1000000 ); int random2 = generator.nextInt( 1000000 ); 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

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:\audioadb -d pull /data/data/com.SQLPlay/databases c:\audio

Play sound

• Get location (done)• Get database entry that is nearest to current

location– Android query– SQL SELECT

• 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<?”; String selectionArgs[] = {“90000000”}– E.g., selection = “lat<? AND type=?”; String selectionArgs[] = {“90000000”, “audio”}

• Groupby and having are for grouping (we set as null)• Orderby is to order the replies (we set as null)• Limit controls how many to return (we set as null)

– If orderBy is used, then limit can be used to get the first or first few– E.g., orderBy = “cost”; limit = “1”; returns the row with the highest cost

public Cursor query (String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy, String limit)

Cursor c = myDatabase.query (“things”, null , null, null, null, null, null, null);

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<c.getColumnCount(); i++) row += c.getString(i) + " "; Log.d("SQLPlay",row); c.moveToNext();

} c.close();

Try it• Make function playAudio and call this function from playButton.onClick• Make function, getfilename• In playAudio, call getFilename• In getFilename, putCursor 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<c.getColumnCount(); i++) row += c.getString(i) + " "; Log.d("SQLPlay",row); c.moveToNext();

} c.close();

Run, select play, and look at log.

String selection = “lat<?”String selectionArgs[] = {“90000000”};

Try other selections

String columns[] = “max(lat)”Everything else null

String selection = “lat BETWEEN ? AND ?”String selectionArgs[] = {“0”, “90000000”};

String selection = “lat IN ”String selectionArgs[] = {“somevalue”};

Exact match(maybe somevalue can be a set?)

String columns[] = “min(abs(lat-70000000))”Everything else null

nearest

• But how to get a nearest point?– I don’t think it is possible with this type of query

• rawQuery– Same as SQLite queries.– Android’s query is easy, but very limited.

rawQuery gives the full power of SQLite– If you know SQL, then you may as well use

rawQuery

SQL SELECT• SELECT column_name(s)• FROM table_name• WHERE column_name operator value

• SELECT * FROM things WHERE lat < 90000000• Try in sqlite3• In shell, # sqlite3 things.db “SELECT * from things” ….

• Smallest lat– SELECT * FROM things WHERE lat in (SELECT min(lat) )

• Nearest lat to 4000000• SELECT * FROM things WHERE abs(lat-40000000) in (SELECT

min(abs(lat-40000000) ) );

– Nearest to La, Lo• SELECT * FROM things WHERE abs(lat - La)+abs(long - Lo) in

(SELECT min(abs(lat - La)+abs(long - Lo) ) );• Don’t forget spaces, -Lo is an invalid string is Lo<0

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, []);

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;

Try it• in getFilename function Location location = locationManager.getLastKnownLocation(provider); Random generator = new Random(); int random1 = generator.nextInt( 1000000 ); int random2 = generator.nextInt( 1000000 ); 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;

finally

• In play, paste code to play audio from previous lecture