3

我想在我的数据库表中使用“ORDER BY”对我的所有数据库条目进行排序。我不知道我做错了什么，但它不起作用。
这是我的代码：

class NoteHelper extends SQLiteOpenHelper {

private static final String DATABASE_NAME = "note.db";
private static final int SCHEMA_VERSION = 1;


public NoteHelper(Context context){
    super(context, DATABASE_NAME, null, SCHEMA_VERSION);
}

@Override
public void onCreate(SQLiteDatabase db){
    db.execSQL("CREATE TABLE Notes (_id INTEGER PRIMARY KEY AUTOINCREMENT, note TEXT);");
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion){
    //no-op, since will not be called until 2nd schema
    //version exists
}

public void insert(String note) {

    ContentValues cv = new ContentValues();
    cv.put("note", note);
    //you must pass it at lease one name of a colum
    getWritableDatabase().insert("Notes", "note", cv);
}

public void update(String id, String note){
    ContentValues cv = new ContentValues();
    String[] args = {id};

    cv.put("note", note);
    getWritableDatabase().update("Notes", cv, "_id=?", args);
}

public void delete(String id){
    getWritableDatabase().delete("Notes", "_id=?", new String[] {id});
}

public Cursor getAll(){
    return (getReadableDatabase().rawQuery("SELECT _id, note FROM Notes",  null));
}


public Cursor getAllSorted(){
    return (getReadableDatabase().rawQuery("SELECT note  FROM Notes  ORDER BY note  COLLATE NOCASE", null));

}

public String getNote(Cursor c){
    return(c.getString(1));
}

public Cursor getById(String id) {
    String[] args = {id};

    return(getReadableDatabase().rawQuery("SELECT _id, note FROM Notes WHERE _id=?", args));
}

 }

如果有人知道问题出在哪里，请帮助我，谢谢。

好的，这是主要代码： 

NoteAdapter adapter = null;
NoteHelper helper = null;
Cursor dataset_cursor = null;
EditText editNote = null;
//this is how track which note we are working on
String noteId = null;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);

    try{


    setContentView(R.layout.history);

    ListView list = (ListView)findViewById(R.id.list);
    editNote = (EditText)findViewById(R.id.myEditText);


    helper = new NoteHelper(this);
    dataset_cursor = helper.getAll();
    startManagingCursor(dataset_cursor);
    adapter = new NoteAdapter(dataset_cursor);
    list.setAdapter(adapter);
class NoteAdapter extends CursorAdapter {
    NoteAdapter(Cursor c){
        super(Ztutorial11.this, c);


    }




    public void bindView(View row, Context ctxt, Cursor c) {
        NoteHolder holder = (NoteHolder)row.getTag();
        holder.populateFrom(c, helper);
    }

    public View newView(Context ctxt, Cursor c, ViewGroup parent) {
        LayoutInflater inflater = getLayoutInflater();
        View row = inflater.inflate(R.layout.row, parent, false);
        NoteHolder holder = new NoteHolder(row);

        row.setTag(holder);
        return (row);
    }
}

static class NoteHolder {
    private TextView noteText = null;

    NoteHolder(View row){
        noteText = (TextView)row.findViewById(R.id.note);


    }

    void populateFrom(Cursor c, NoteHelper helper) {
        noteText.setText(helper.getNote(c));
    }
}



   public boolean onCreateOptionsMenu(Menu menu){
super.onCreateOptionsMenu(menu);
MenuInflater awesome = getMenuInflater();
awesome.inflate(R.menu.menu_expresions, menu);
return true;

   }
   public boolean onOptionsItemSelected(MenuItem item){
switch(item.getItemId()){
case R.id.Az:

    //something to do
    helper.getAllSorted();
    //update the view
    dataset_cursor.requery();
    return true;
case R.id.Za:

    //something to do

    return true;
case R.id.deleteall:

    //something to do
    helper.deleteAll();
    dataset_cursor.requery();
    return true;
case R.id.undo:

    //something to do

    return true;

}

return false;
 }



 };
4

3 回答 3

2 
dataset_cursor = helper.getAll();

你没有用getAllSorted()...

此外，onOptionsItemSelected()没有在任何地方被调用，即使被调用，调用的返回值getAllSorted()也没有被使用。

于 2012-08-14T17:56:36.750 回答
1

试试这样：

public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        case R.id.Az:
            dataset_cursor = helper.getAllSorted();
            adapter.changeCursor(dataset_cursor);
            return true;
        case R.id.Za:
            // something to do
            return true;
        case R.id.deleteall:
            // something to do
            helper.deleteAll();
            dataset_cursor.requery();
            adapter.notifyDataSetChanged();
            return true;
        case R.id.undo:
            // something to do
            return true;
    }
    return false;
}

首先将新的排序结果分配给dataset_cursor适配器，然后告诉适配器光标已更改。该deleteall案例可能需要adapter.notifyDataSetChanged();我在那里添加的行。

于 2012-08-14T18:10:42.333 回答
1

我不知道，但这里有一些猜测/尝试。

1) note 之后和 COLLATE 之前似乎有两个空格。不确定这是否会有所作为。（事实上​​，该 SQL 字符串的几个不同位置似乎有额外的空格）

2) 当您删除 COLLATE NOCASE 子句时会发生什么？只是想知道这是否是问题所在，或者是否是实际的 ORDER BY 子句失败了。

3）COLLATE NOCASE后是否需要指定ASC/DESC？

于 2012-08-14T16:33:04.577 回答