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안드로이드를 사용하여 SQLite 데이터베이스를 쿼리하는 데 문제가 있습니다. 테이블에 "users"가 DB에 존재하지 않거나 "fname"열 이름이 존재하지 않지만 둘 다 존재한다는 오류가 계속 발생합니다.안드로이드 : 데이터베이스에 테이블이 없다고 주장하는 오류가 있지만
데이터베이스에서 인식 할 수있는 유일한 테이블은 android_metadata입니다.
public class DataBaseHelper extends SQLiteOpenHelper{
//The Android's default system path of your application database.
private static String DB_PATH = "/data/data/com.Main/databases/";
private static String DB_NAME = "CSLearnDB";
private SQLiteDatabase myDataBase;
private final Context myContext;
/**
* Constructor
* Takes and keeps a reference of the passed context in order to access to the application assets and resources.
* @param context
*/
public DataBaseHelper(Context context) {
super(context, DB_NAME, null, 1);
this.myContext = context;
}
public void createDataBase() throws IOException{
boolean dbExist = checkDataBase();
if(dbExist){
//do nothing - database already exist
}else{
//By calling this method and empty database will be created into the default system path
//of your application so we are gonna be able to overwrite that database with our database.
this.getReadableDatabase();
try {
this.close();
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
this.close();
}
/**
* Check if the database already exist to avoid re-copying the file each time you open the application.
* @return true if it exists, false if it doesn't
*/
private boolean checkDataBase(){
SQLiteDatabase checkDB = null;
try{
String myPath = DB_PATH + DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}catch(SQLiteException e){
//database does't exist yet.
}
if(checkDB != null){
checkDB.close();
}
return checkDB != null ? true : false;
}
/**
* Copies your database from your local assets-folder to the just created empty database in the
* system folder, from where it can be accessed and handled.
* This is done by transfering bytestream.
* */
private void copyDataBase() throws IOException{
//Open your local db as the input stream
InputStream myInput = myContext.getAssets().open(DB_NAME);
// Path to the just created empty db
String outFileName = DB_PATH + DB_NAME;
//Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFileName);
//transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer))>0){
myOutput.write(buffer, 0, length);
}
//Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
}
public void openDataBase() throws SQLException{
//Open the database
String myPath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}
@Override
public synchronized void close() {
if(myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public Cursor dbSelect(String table, String[] select){
return myDataBase.query(table, select, null, null, null, null, null);
}
}
가 여기 내 홈페이지에서 onCreate 메소드의 코드입니다 : 어떤 도움이 정말 감사하겠습니다
public class Hello_AppActivity extends Activity {
String tag = "Events";
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
DataBaseHelper myDbHelper = new DataBaseHelper(this);
try {
myDbHelper.createDataBase();
} catch (IOException ioe) {
throw new Error("Unable to create database");
}
try {
myDbHelper.openDataBase();
}catch(SQLException sqle){
throw sqle;
}
ArrayList<String> results = new ArrayList<String>();
results.add("TEST");
String[] x = {"sname"};
Cursor c = myDbHelper.dbSelect("users", x);
Spinner s1 = (Spinner) findViewById(R.id.spinner1);
if (c != null) {
if (c.moveToFirst()) {
do {
String firstName = c.getString(0);
results.add(firstName);
results.add("TEST 2");
}while (c.moveToNext());
}
}else{
}
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item, results);
s1.setAdapter(adapter);
}
여기 DataBaseHelper 클래스 내 코드입니다. 감사.
새 테스트 데이터베이스가 만들어져 성공적으로 작동했습니다. 감사. – TrueWheel