无法回滚 - 第一次执行应用程序时没有事务处于活动状态

Question

我正在以这种方式创建DataBase：

MainActivity：

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    BBDD bbdd=new BBDD(MainActivity.this);
    SQLiteDatabase db=bbdd.getWritableDatabase();

}
}

BBDD：

public class BBDD extends SQLiteOpenHelper {

public static final int DATABASE_VERSION = 1;
public static final String DATABASE_NAME = "users.db";
public String TABLE_USERS="users";
public String TABLE_SKILLS="skills";
public String TABLE_USERTYPES="tipousuarios";
public Context ctx;

public BBDD(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
    ctx=context;
}

@Override
public void onCreate(SQLiteDatabase db) {
    Log.i("David", "onCreate de BBDD");
    dropTables();
    //db=getWritableDatabase();
    poblarTablas(db);
}

private void poblarTablas(SQLiteDatabase db) {

    Log.i("David", "Creando tablas");
    //Creamos las tablas
    db.execSQL("CREATE TABLE "+TABLE_USERS+" ("+
    "id INTEGER PRIMARY KEY, "+
    "nombre TEXT NOT NULL, "+
    "apellidos TEXT NOT NULL, "+
    "tipoUsuario TEXT NOT NULL, "+
    "login TEXT NOT NULL, "+
    "password TEXT NOT NULL)");

    Log.i("David", "Tabla users creada");

    db.execSQL("CREATE TABLE"+TABLE_SKILLS+" ("+
    "id INTEGER PRIMARY KEY, "+
    "user TEXT FOREIGN KEY REFERENCES "+TABLE_USERS+"(login), "+
    "habilidad TEXT NOT NULL)");

    Log.i("David", "Tabla skills creada");

    db.execSQL("CREATE TABLE "+TABLE_USERTYPES+"( "+
    "id INTEGER PRIMARY KEY, "+
    "tipousuario TEXT NOT NULL)");

    Log.i("David", "Tabla tipos de usuarios creada");

    //Insertamos los tipos de usuario
    ContentValues valuesTipoUsuario=new ContentValues();
    valuesTipoUsuario.put("tipousuario","administrador");
    db.insert(TABLE_USERTYPES,null,valuesTipoUsuario);

    ContentValues valuesTipoUsuario2=new ContentValues();
    valuesTipoUsuario2.put("tipousuario", "técnico");
    db.insert(TABLE_USERTYPES, null, valuesTipoUsuario2);

    //Insertamos usuarios
    ContentValues values=new ContentValues();
    values.put("nombre", "Rubén");
    values.put("apellidos", "García López");
    values.put("tipoUsuario", "administrador");
    values.put("login", "rgarcia");
    values.put("password", "rgarcia");

    db.insert(TABLE_USERS, null, values);
    ContentValues values2=new ContentValues();
    values2.put("nombre", "Rafael");
    values2.put("apellidos", "Martín González");
    values2.put("tipoUsuario", "técnico");
    values2.put("login", "rmartin");
    values2.put("password", "rmartin");

    db.insert(TABLE_USERS, null, values2);
    ContentValues values3=new ContentValues();
    values3.put("nombre", "Sarah");
    values3.put("apellidos", "López Martínez");
    values3.put("tipoUsuario", "técnico");
    values3.put("login", "slopez");
    values3.put("password", "slopez");
    db.insert(TABLE_USERS, null, values3);

    ContentValues values4=new ContentValues();
    values3.put("nombre", "David");
    values3.put("apellidos", "Fernández Arias");
    values3.put("tipoUsuario", "técnico");
    values3.put("login", "dfernandez");
    values3.put("password", "dfernandez");
    db.insert(TABLE_USERS, null, values4);

    ContentValues values5=new ContentValues();
    values3.put("nombre", "Pilar");
    values3.put("apellidos", "García Cabrera");
    values3.put("tipoUsuario", "técnico");
    values3.put("login", "pgarcia");
    values3.put("password", "pgarcia");
    db.insert(TABLE_USERS, null, values5);

    //Insertamos las habilidades de los usuarios
    ContentValues vSkills=new ContentValues();
    vSkills.put("user", "rmartin");
    vSkills.put("habilidad", "Reponedor de productos");
    db.insert(TABLE_SKILLS, null, vSkills);

    ContentValues vSkills2=new ContentValues();
    vSkills2.put("user", "smartinez");
    vSkills2.put("habilidad", "Envolver");
    db.insert(TABLE_SKILLS, null, vSkills2);

    ContentValues vSkills3=new ContentValues();
    vSkills3.put("user", "dfernandez");
    vSkills3.put("habilidad", "Envolver");
    db.insert(TABLE_SKILLS, null, vSkills3);

    ContentValues vSkills4=new ContentValues();
    vSkills4.put("user", "dfernandez");
    vSkills4.put("habilidad", "Reponedor de productos");
    db.insert(TABLE_SKILLS, null, vSkills4);

    ContentValues vSkills5=new ContentValues();
    vSkills5.put("user", "pgarcia");
    vSkills5.put("habilidad", "Cobrar");
    db.insert(TABLE_SKILLS, null, vSkills5);
}

private void dropTables() {
    Log.i("David", "Eliminando tablas");
    ctx.deleteDatabase(DATABASE_NAME);
}

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

}
}

这样，我收到了例外：

E/SQLiteLog: (1802) os_unix.c:30027: (2) stat(/data/data/com.prueba.sdos.pruebasdos/databases/users.db) - 
E/SQLiteLog: (1802) statement aborts at 9: [CREATE TABLE users (id INTEGER PRIMARY KEY, nombre TEXT NOT NULL, apellidos TEXT NOT NULL, tipoUsuario TEXT NOT NULL, login TEXT NOT NULL, password TEXT NOT NULL)] 
E/SQLiteLog: (1) statement aborts at 2: [ROLLBACK;] cannot rollback - no transaction is active
D/AndroidRuntime: Shutting down VM
W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0x4157fd88)
E/AndroidRuntime: FATAL EXCEPTION: main
              Process: com.prueba.sdos.pruebasdos, PID: 8734
              java.lang.RuntimeException: Unable to start activity ComponentInfo{com.prueba.sdos.pruebasdos/com.prueba.sdos.pruebasdos.MainActivity}: android.database.sqlite.SQLiteException: cannot rollback - no transaction is active (code 1)
                  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2263)
                  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2313)
                  at android.app.ActivityThread.access$800(ActivityThread.java:144)
                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1246)
                  at android.os.Handler.dispatchMessage(Handler.java:106)
                  at android.os.Looper.loop(Looper.java:136)
                  at android.app.ActivityThread.main(ActivityThread.java:5212)
                  at java.lang.reflect.Method.invokeNative(Native Method)
                  at java.lang.reflect.Method.invoke(Method.java:515)
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:602)
                  at dalvik.system.NativeStart.main(Native Method)
               Caused by: android.database.sqlite.SQLiteException: cannot rollback - no transaction is active (code 1)
                  at android.database.sqlite.SQLiteConnection.nativeExecute(Native Method)
                  at android.database.sqlite.SQLiteConnection.execute(SQLiteConnection.java:555)
                  at android.database.sqlite.SQLiteSession.endTransactionUnchecked(SQLiteSession.java:439)
                  at android.database.sqlite.SQLiteSession.endTransaction(SQLiteSession.java:401)
                  at android.database.sqlite.SQLiteDatabase.endTransaction(SQLiteDatabase.java:522)
                  at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:263)
                  at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:164)
                  at com.prueba.sdos.pruebasdos.MainActivity.onCreate(MainActivity.java:15)
                  at android.app.Activity.performCreate(Activity.java:5240)
                  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1088)
                  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2227)
                  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2313) 
                  at android.app.ActivityThread.access$800(ActivityThread.java:144) 
                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1246) 
                  at android.os.Handler.dispatchMessage(Handler.java:106) 
                  at android.os.Looper.loop(Looper.java:136) 
                  at android.app.ActivityThread.main(ActivityThread.java:5212) 
                  at java.lang.reflect.Method.invokeNative(Native Method) 
                  at java.lang.reflect.Method.invoke(Method.java:515) 
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:602) 
                  at dalvik.system.NativeStart.main(Native Method) 

我在升级DDBB时已经读过关于这个错误的信息，但是第一次执行应用程序时会发生这种情况。

有人可以帮忙吗？

谢谢。