데이터베이스 연동 문제 질문 드립니다 !!

Question

public class MainActivity extends AppCompatActivity {

    EditText edt1,edt2,rst1,rst2;
    String str1,str2,num;
    Button insert,delete,view;
    myDBHelper myHelper;
    SQLiteDatabase sqlDB;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        edt1 = (EditText)findViewById(R.id.name);
        edt2 = (EditText)findViewById(R.id.number);
        rst1 = (EditText)findViewById(R.id.rst1);
        rst2=(EditText)findViewById(R.id.rst2);
        insert=(Button)findViewById(R.id.insert);
        delete=(Button)findViewById(R.id.delete);
        view=(Button)findViewById(R.id.view);

        myHelper = new myDBHelper(this);

        insert.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                str1= edt1.getText().toString();
                str2 = edt2.getText().toString();
                if(!str1.isEmpty() && !str2.isEmpty()) {
                    sqlDB = myHelper.getWritableDatabase();
                  @@  //sqlDB.execSQL("INSERT INTO contacts VALUES (null, '" + str1 + "', '" + str2 + "');");
                    sqlDB.close();

                    Toast.makeText(getApplicationContext(), "입력됨", Toast.LENGTH_SHORT).show();
                    edt1.setText("");
                    edt2.setText("");
                }
                else {
                    Toast.makeText(getApplicationContext(), "정보를 입력하세요", Toast.LENGTH_SHORT).show();
                }

            }
        });

       
    }

    public class myDBHelper extends SQLiteOpenHelper{
        public myDBHelper(Context context){
            super(context, "groupdb", null,1);
        }

        @Override
        public void onCreate(SQLiteDatabase db) {

            db.execSQL("CREATE TABLE contacts (_id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT, tel            TEXT)");

        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
             db.execSQL("DROP TABLE IF EXISTS contacts");
            onCreate(db);
        }
    }
}
 
 
주석처리한 한줄을 주석 처리안하고  돌리면 insert버튼 클릭시 팅기는데,,
주석처리를 해주면 팅기지 않아서 이 줄이 문제인듯한데 뭐가 틀린건지 잘 모르겠네요 ....... 고수님들 조언 부탁드립니다 !!