public class accountsDB {
 private static final String DATABASE_NAME = "accounts.db"; 
 private static final String DATABASE_TABLE = "accounts"; 
 private static final int DATABASE_VERSION = 1;
 
 public static final String KEY_ID = "_id";
 public static final String KEY_USERNAME = "username"; 
 public static final String KEY_PASSWORD = "password"; 
 
 private static final String DATABASE_CREATE = 
  "create table data (_id integer primary key autoincrement,"+ 
  "username text not null, password text not null);";
 
 private static final String TAG = "AccountsDb";
 private static DbHelper mDbHelper;
 private SQLiteDatabase mDb;
 private final Context mCtx;
 
 private static class DbHelper extends SQLiteOpenHelper { 
  public DbHelper (Context context) { //데이터베이스에 대한 정보를 저장하는 역할
  super(context, DATABASE_NAME, null, DATABASE_VERSION);
  }

  @Override
  public void onCreate(SQLiteDatabase db) { //실행 직후 수행되어야 할 것 
  db.execSQL(DATABASE_CREATE); // 테이블 생성
  }

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

 public accountsDB(Context ctx){ 
 this.mCtx = ctx; 
 } 

 public accountsDB open() throws SQLException{ 
 mDbHelper = new DbHelper(mCtx);
 mDb = mDbHelper.getWritableDatabase();
 //mDb = mDbHelper.getReadableDatabase();
 return this; 
 }
 
 public void close(){ 
 mDbHelper.close();
 }
 
 public long createAccount(String name, String pass){ // 레코드 생성 
 ContentValues initialValues = new ContentValues(); 
 initialValues.put(KEY_USERNAME, name); 
 initialValues.put(KEY_PASSWORD, pass); 
 return mDb.insert(DATABASE_TABLE, null, initialValues); 
 }
 
 public boolean deleteAccount(long rowID){ // 레코드 삭제 
 return mDb.delete(DATABASE_TABLE, KEY_ID + "=" + rowID, null) > 0; 
 }
   
 public Cursor fetchAllAccount(){ // 모든 레코드 반환 
 return mDb.query(DATABASE_TABLE, new String[]{KEY_ID, KEY_USERNAME, KEY_PASSWORD}, null, null, null, null, null); 
 } 
    
 public Cursor fetchAccount(long rowID) throws SQLException{ // 특정 레코드 반환 
 Cursor mCursor = 
 mDb.query(true, DATABASE_TABLE, new String[]{KEY_ID, KEY_USERNAME, KEY_PASSWORD}, KEY_ID + "=" + rowID, null, null, null, null, null); 
  if(mCursor != null) 
 mCursor.moveToFirst(); 
 return mCursor; 
 } 
  
 public boolean updateAccount(long rowID, String name, String pass){ // 레코드 수정 
 ContentValues args = new ContentValues(); 
 args.put(KEY_USERNAME, name); 
 args.put(KEY_PASSWORD, pass); 
 return mDb.update(DATABASE_TABLE, args, KEY_ID + "=" + rowID, null) > 0; 
 }
}

public void click_ok(View target)
 {
  final EditText input_id = (EditText)findViewById(R.id.id_input);
     final EditText input_pw = (EditText)findViewById(R.id.password_input);
     
     username = (String)input_id.getText().toString();
   password = (String)input_pw.getText().toString();
   
   mDbHelper = new accountsDB(this);
  mDbHelper.open();      
   mDbHelper.createAccount(username, password);
    
   mDbHelper.close();
   input_id.setText("");
   input_pw.setText("");
   finish();
 }