java - 从后向读取Sql数据库

Question

嘿伙计，我有一个问题。我怎样才能从后面读取我的Sql数据。我尝试了很多在网上找到的东西，但我的代码没有任何作用:

public Cursor getAllRows() {
    String where = null;
    Cursor c =  db.query(true, DATABASE_TABLE, ALL_KEYS, 
                        where, null, null, null,null,null);
    if (c != null) {
        c.moveToFirst();
    }
    return c;

以及光标的代码:

Cursor cursor = myDb.getAllRows();

// Allow activity to manage lifetime of the cursor.
// DEPRECATED! Runs on the UI thread, OK for small/short queries.
startManagingCursor(cursor);

// Setup mapping from cursor to view fields:
String[] fromFieldNames = new String[] 
        {DBAdapter.KEY_KALO, DBAdapter.KEY_HYDRATE, DBAdapter.KEY_FAT, DBAdapter.KEY_PROTEIN ,DBAdapter.KEY_CAL};
int[] toViewIDs = new int[]
        {R.id.item_Kalorien,     R.id.item_KG_in_g,           R.id.item_F_in_g,     R.id.item_P_in_g,R.id.item_cal};

// Create adapter to may columns of the DB onto elemesnt in the UI.
SimpleCursorAdapter myCursorAdapter = 
        new SimpleCursorAdapter(
                this,       // Context
                R.layout.item_tagebuch, // Row layout template
                cursor,                 // cursor (set of DB records to map)
                fromFieldNames,         // DB Column names
                toViewIDs               // View IDs to put information in
                );

// Set the adapter for the list view
ListView myList = (ListView) findViewById(R.id.listView1);
myList.setAdapter(myCursorAdapter);

谢谢你的帮助，很抱歉我的英语不好:)

Answer 1

“从后面”的说法不明确，我假设您想以特定顺序读取数据库

如果您想按字段的降序阅读，请说“foo”，然后

String ORDER = "foo DESC";/*使用 ASC 升序*/

并按如下方式更改 cod

public Cursor getAllRows() {
    String where = null;
    String Order = "foo DESC";
    Cursor c =  db.query(true, DATABASE_TABLE, ALL_KEYS, 
                        where, null, null, null,Order,null);
    if (c != null) {
        c.moveToFirst();
    }
    return c;

这是查询的语法

公共(public)游标查询(字符串表、字符串[]列、字符串选择、字符串[]selectionArgs、字符串 groupBy、字符串having、字符串 orderBy、字符串 limit)

请参阅以下链接以获取进一步说明 SQLiteDatabase Android