DBAdapter (friend)

package se.muradi.enayatullah.uppgift3;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

public class DBAdapter {
    static final String KEY_ROWID = "id";
    static final String KEY_DATUM = "datum";
    static final String KEY_TYP = "typ";
    static final String KEY_SUMMA = "summa";
    static final String TAG = "DBAdapter";
    static final String DATABASE_NAME = "BudgetDB";
    static final String DATABASE_TABLE = "information";
    static final int DATABASE_VERSION = 1;
    static final String DATABASE_CREATE = "create table information (id integer primary key autoincrement, "
            + "datum text not null, typ text not null, summa text not null);";
    final Context context;
    DatabaseHelper DBHelper;
    SQLiteDatabase db;

    public DBAdapter(Context ctx) {
        this.context = ctx;
        DBHelper = new DatabaseHelper(context);
    }

    private static class DatabaseHelper extends SQLiteOpenHelper {
        DatabaseHelper(Context context) {
            super(context, DATABASE_NAME, null, DATABASE_VERSION);
        }

        @Override
        public void onCreate(SQLiteDatabase db) {
            try {
                db.execSQL(DATABASE_CREATE);
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
                    + newVersion + ", which will destroy all old data");
            db.execSQL("DROP TABLE IF EXISTS contacts");
            onCreate(db);
        }
    }

    // ---opens the database---
    public DBAdapter open() throws SQLException {
        db = DBHelper.getWritableDatabase();
        return this;
    }

    // ---closes the database---
    public void close() {
        DBHelper.close();
    }

    // ---insert a contact into the database---
    public long insertContact(String datum, String typ, String summa) {
        ContentValues initialValues = new ContentValues();
        initialValues.put(KEY_DATUM, datum);
        initialValues.put(KEY_TYP, typ);
        initialValues.put(KEY_SUMMA, summa);
        return db.insert(DATABASE_TABLE, null, initialValues);
    }

    // ---deletes a particular contact---
    public boolean deleteContact(long rowId) {
        return db.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0;
    }

    // ---retrieves all the contacts---
    public Cursor getAllContacts() {
        return db.query(DATABASE_TABLE, new String[] { KEY_ROWID, KEY_DATUM,
                KEY_TYP, KEY_SUMMA }, null, null, null, null, null);
    }

    // ---retrieves a particular contact---
    public Cursor getContact(String typ) throws SQLException {
        Cursor mCursor = db.query(true, DATABASE_TABLE, new String[] {
                KEY_ROWID, KEY_DATUM, KEY_TYP, KEY_SUMMA }, KEY_TYP + "= '" + typ + "'",
                null, null, null, null, null);
        if (mCursor != null) {
            mCursor.moveToFirst();
        }
        return mCursor;
    }

    // ---updates a contact---
    public boolean updateContact(long rowId, String datum, String typ, String summa) {
        ContentValues args = new ContentValues();
        args.put(KEY_DATUM, datum);
        args.put(KEY_TYP, typ);
        args.put(KEY_SUMMA, summa);
        return db.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) > 0;
    }
}