我从表中检索 ID 时遇到问题。
在项目中，我有 SQLite 数据库，其中包含两个表：学生和部门。
部门表由我完成。我通过 Spinner 从该表中读取数据。如何从表中获取部门的 ID 并将其保存到学生表中？
我不想将数据保存到部门表中，因为它已经完成了。
AddActivity.class：
public class AddActivity extends AppCompatActivity implements OnClickListener {
private DatabaseHandler dbCreate;
EditText etImie, etNazwisko, etIndeks, etEmail, etWydzial, etKierunek, etTelefon, etShow;
Button btnSave, btnDisplay;
Spinner spSpinner;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
etImie = (EditText) findViewById(R.id.etImie);
etNazwisko = (EditText) findViewById(R.id.etNazwisko);
etIndeks = (EditText) findViewById(R.id.etIndeks);
etEmail = (EditText) findViewById(R.id.etEmail);
// etWydzial = (EditText) findViewById(R.id.etWydzial);
etKierunek = (EditText) findViewById(R.id.etKierunek);
etTelefon = (EditText) findViewById(R.id.etTelefon);
etShow = (EditText) findViewById(R.id.etShow);
spSpinner = (Spinner) findViewById(R.id.spSpinner);
btnSave = (Button) findViewById(R.id.btnSave);
btnSave.setOnClickListener(this);
btnDisplay = (Button) findViewById(R.id.btnDisplay);
btnDisplay.setOnClickListener(this);
dbCreate = new DatabaseHandler(this.getApplicationContext());
ArrayList<String> list = dbCreate.getAllDepartments();
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.support_simple_spinner_dropdown_item,list);
spSpinner.setAdapter(adapter);
}
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu_baza_stud, menu);
return true;
}
private void insertInStudentTable(String imie, String nazwisko, int indeks, String email, String wydzial, String kierunek, String telefon) {
SQLiteDatabase db = dbCreate.getWritableDatabase();
ContentValues data_2 = new ContentValues();
data_2.put("wydzial", wydzial);
data_2.put("kierunek", kierunek);
long idOfDepart = db.insertOrThrow("departments", null, data_2);
ContentValues data = new ContentValues();
data.put("imie", imie);
data.put("nazwisko", nazwisko);
data.put("indeks", indeks);
data.put("email", email);
data.put("numer", telefon);
data.put("dept_id", idOfDepart);
db.insertOrThrow("students", null, data);
}
public void onClick(View v) {
if(v.getId() == R.id.btnSave) {
try {
String imie = etImie.getText().toString();
String nazwisko = etNazwisko.getText().toString();
String sIndex = etIndeks.getText().toString();
int indeks = Integer.parseInt(sIndex);
String email = etEmail.getText().toString();
String wydzial = etWydzial.getText().toString();
String kierunek = etKierunek.getText().toString();
String telefon = etTelefon.getText().toString();
if(imie.length() == 0 || nazwisko.length() == 0 || sIndex.length() == 0 || email.length() == 0 || wydzial.length() == 0 || kierunek.length() == 0 || telefon.length() == 0){
Toast.makeText(getApplicationContext(),"Fill data.", Toast.LENGTH_SHORT).show();
}else{
insertInStudentTable(imie, nazwisko, indeks, email, wydzial, kierunek, telefon);
Toast.makeText(getApplicationContext(), "Student has been created: " + imie + " " + nazwisko + " .", Toast.LENGTH_SHORT).show();
}
} catch (SQLiteException e) {
System.err.println(e.toString());
} finally {
dbCreate.close();
}
}
}// end of onClick method}
DatabaseHandler.class：
public class DatabaseHandler extends SQLiteOpenHelper {
private static final int DATABASE_VERSION = 2;
private static final String TAG = "DatabaseHandler";
private static final String DATABASE_NAME = "studencibazadb.db";
private static final String ID_COLUMN = "id";
// pola tabeli "wydzial"
public static final String TABLE_DEPARTMENTS = "departments",
KEY_DEPARTMENT = "wydzial",
KEY_SPECIALIZATION = "kierunek";
// pola tabeli "students"
public static final String TABLE_STUDENTS = "students",
KEY_FIRSTNAME = "imie",
KEY_SURNAME = "nazwisko",
KEY_INDEKS = "indeks",
KEY_EMAIL = "email",
KEY_NUMER = "numer",
STUDENT_DEPARTMENT_ID = "dept_id";
public DatabaseHandler(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE " + TABLE_DEPARTMENTS + "(" + ID_COLUMN + " INTEGER PRIMARY KEY AUTOINCREMENT," + KEY_DEPARTMENT + " TEXT NOT NULL," + KEY_SPECIALIZATION + " TEXT NOT NULL)");
db.execSQL("CREATE TABLE " + TABLE_STUDENTS + "(" + ID_COLUMN + " INTEGER PRIMARY KEY AUTOINCREMENT," + KEY_FIRSTNAME + " TEXT NOT NULL," + KEY_SURNAME + " TEXT NOT NULL," + KEY_INDEKS + " INTEGER NOT NULL," + KEY_EMAIL + " TEXT NOT NULL," + KEY_NUMER + " TEXT NOT NULL," + STUDENT_DEPARTMENT_ID + " INT)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_DEPARTMENTS);
db.execSQL("DROP TABLE IF EXISTS " + TABLE_STUDENTS);
onCreate(db);
}
public ArrayList<String> getAllDepartments() {
ArrayList<String> list = new ArrayList<String>();
SQLiteDatabase db = this.getReadableDatabase();
db.beginTransaction();
try{
String selectQuery = "SELECT * FROM " + TABLE_DEPARTMENTS;
Cursor cursor = db.rawQuery(selectQuery, null);
if(cursor.getCount() > 0){
while(cursor.moveToNext()){
String depname = cursor.getString(cursor.getColumnIndex("wydzial"));
list.add(depname);
}
}
db.setTransactionSuccessful();
}catch(SQLiteException e){
e.printStackTrace();
}
finally{
db.endTransaction();
db.close();
}
return list;
}
}