Android - ขอสอบถาม inner join หน่อยครับ สงสัย ขอคำปรึกษา พอดี ผมไม่ค่อย เก่ง ในเรื่อง พวกนี้เท่าไหร่

class MyDbHelper extends SQLiteOpenHelper {
	private static final String DB_NAME = "MYDBSQL";
    private static final int DB_VERSION = 1;
    
    public static final String TABLE_COURES = "Coures";
    public static final String TABLE_STU = "Student";
 

    public static final String COU_ID = "IDCoures";
    public static final String COU_NAME = "CouresName";
    
    public static final String STU_COU = "IDCoures";
    public static final String STU_ID = "IDstudent";
    public static final String STU_NAME = "studentname";
    public static final String STU_LESTNAME = "Studentlastname";
    
public void onCreate(SQLiteDatabase db) {
		db.execSQL("CREATE TABLE "+ TABLE_COURES +
				"(_idINTEGER PRIMARY KEY, " 
        		+ COU_ID + " TEXT, "
				+ COU_NAME + " TEXT);");
		
		db.execSQL("CREATE TABLE "+ TABLE_STU +
				"(idINT PRIMARY KEY, "
				+ STU_COU + " TEXT, "
				+ STU_ID + " TEXT, "
				+ STU_NAME + " TEXT, "
				+ STU_LESTNAME+ " TEXT);");
			@Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
		db.execSQL("DROP TABLE IF EXISTS "+ TABLE_COURES);
        db.execSQL("DROP TABLE IF EXTSTS "+ TABLE_STU);
        db.execSQL(SQL_DELETE_ALARM);
        onCreate(db);
    }
}

public class ClassList extends Activity{
	MyDbHelper myHelper;
	SQLiteDatabase mDb;
	Cursor mCursor;
	

	
	ArrayList<String> arr_list;
	    ListView lv; 

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		setContentView(R.layout.class_list);
		
		ListView listView1 = (ListView)findViewById(R.id.classlistView1);
		
		
		myHelper = new MyDbHelper(this);
		
		mDb = myHelper.getReadableDatabase();
		mCursor = mDb.rawQuery("SELECT " + MyDbHelper.COU_ID 
				+ ", "  + MyDbHelper.COU_NAME
                + " FROM " + MyDbHelper.TABLE_COURES, null); 
		
        arr_list = new ArrayList<String>();
        
        mCursor.moveToFirst();

        while ( !mCursor.isAfterLast()){
            arr_list.add(mCursor.getString(mCursor.getColumnIndex
                    (MyDbHelper.COU_ID)));

        mCursor.moveToNext(); 
        }
        
        lv = (ListView)findViewById(R.id.classlistView1);
        lv.setAdapter(updateListView());
        lv.setAdapter(new ArrayAdapter<String>(this
                , android.R.layout.simple_list_item_1, arr_list));
        lv.setOnItemClickListener(new OnItemClickListener() {

			@Override
			public void onItemClick(AdapterView<?> arg0
                    , View arg1, int arg2, long arg3) {
                Intent intent;
                switch(arg2) {
                case 0 : 
                    intent = new Intent(getApplicationContext()		\\บรรทัดนี้ ผมจองไว้สำหรับ กดในส่วนที่เป็นlist เพื่อให้ไปอีกหน้านึง และจะให้โชว์ที่ join กันแต่ละรายวิชาครับ
                            , StuList.class);
                    startActivity(intent);
                    break;
                case 1 : 
                    intent = new Intent(getApplicationContext()
                            , StuList.class);
                    startActivity(intent);
                    break;
                case 2 : 
                    intent = new Intent(getApplicationContext()
                            , StuList.class);
                    startActivity(intent);
                    break;
                case 3 : 
                    intent = new Intent(getApplicationContext()
                            , StuList.class);
                    startActivity(intent);
                    break;
                case 4 : 
                    intent = new Intent(getApplicationContext()
                            , StuList.class);
                    startActivity(intent);
                    break;
                case 5 : 
                    intent = new Intent(getApplicationContext()
                            , StuList.class);
                    startActivity(intent);
                    break;
                case 6 : 
                    intent = new Intent(getApplicationContext()
                            , StuList.class);
                    startActivity(intent);
                    break;
                case 7 : 
                    intent = new Intent(getApplicationContext()
                            , StuList.class);
                    startActivity(intent);
                    break;
                case 8 : 
                    intent = new Intent(getApplicationContext()
                            , StuList.class);
                    startActivity(intent);
                    break;
                case 9 : 
                    intent = new Intent(getApplicationContext()
                            , StuList.class);
                    startActivity(intent);
                    break;
                case 10 : 
                    intent = new Intent(getApplicationContext()
                            , StuList.class);
                    startActivity(intent);
                    break;
                }
			}