以降序显示数据的最有效方法是什么？
public String getRank() {
String[] rank = new String[]{ KEY_ROWID };
Cursor c = scoreDb.query(DATABASE_TABLE, rank, null, null, null, null, null); //reading information from db.
String rankResult = "";
int iRow = c.getColumnIndex(KEY_ROWID); //Cursor looking for column setting equal to these ints.
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()) {
//Move to first row - where cursor starts and moves to next row as long it is not after last row.
rankResult = rankResult + c.getString(iRow) + "\n";
//Returning value of row that it is currently on.
}
return rankResult; //returning result
}
public String getName() {
String[] name = new String[]{ KEY_NAME };
Cursor c = scoreDb.query(DATABASE_TABLE, name, null, null, null, null, null); //reading information from db.
String nameResult = "";
int iRow1 = c.getColumnIndex(KEY_NAME); //Cursor looking for column setting equal to these ints.
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()) {
//Move to first row - where cursor starts and moves to next row as long it is not after last row.
nameResult = nameResult + c.getString(iRow1) + "\n";
//Returning value of row that it is currently on.
}
return nameResult; //returning result
}
public String getScore() {
String[] score = new String[]{ KEY_SCORE };
Cursor c = scoreDb.query(DATABASE_TABLE, score, null, null, null,null, null); //reading information from db.
String scoreResult = "";
int iRow2 = c.getColumnIndex(KEY_SCORE); //Cursor looking for column setting equal to these ints.
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()) {
//Move to first row - where cursor starts and moves to next row as long it is not after last row.
scoreResult = scoreResult + c.getString(iRow2) + "\n";
//Returning value of row that it is currently on.
}
return scoreResult; //returning result
}
答案 0 :(得分：168)
Query有两种语法，你使用的语法，最后一列代表orderBy，你只需要指定你要做什么列orderBy +“ASC”（或）orderBy +“DESC”
Cursor c = scoreDb.query(DATABASE_TABLE, rank, null, null, null, null, yourColumn+" DESC");
请参阅this文档，了解有关query()方法的更多信息。
答案 1 :(得分：12)
Cursor c = scoreDb.query(Table_Name, score, null, null, null, null, Column+" DESC");
试试这个
答案 2 :(得分：11)
return database.rawQuery("SELECT * FROM " + DbHandler.TABLE_ORDER_DETAIL +
" ORDER BY "+DbHandler.KEY_ORDER_CREATED_AT + " DESC"
, new String[] {});
答案 3 :(得分：4)
根据docs：
public Cursor query (String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy, String limit);
您的 ORDER BY 参数意味着：
如何对行进行排序，格式为SQL ORDER BY子句 （不包括ORDER BY本身）。传递null将使用默认值 排序顺序，可能是无序的。
因此，您的查询将是：
Cursor cursor = db.query(TABLE_NAME, null, null,
null, null, null, KEY_ITEM + " DESC", null);
答案 4 :(得分：4)
public List getExpensesList(){
SQLiteDatabase db = this.getWritableDatabase();
List<String> expenses_list = new ArrayList<String>();
String selectQuery = "SELECT * FROM " + TABLE_NAME ;
Cursor cursor = db.rawQuery(selectQuery, null);
try{
if (cursor.moveToLast()) {
do{
String info = cursor.getString(cursor.getColumnIndex(KEY_DESCRIPTION));
expenses_list.add(info);
}while (cursor.moveToPrevious());
}
}finally{
cursor.close();
}
return expenses_list;
}
这是我从数据库中读取列表视图的记录的方式，按降序排列。在获取每条记录后，将光标移动到最后并移动到上一条记录。希望这有帮助〜
答案 5 :(得分：3)
Cursor c = myDB.rawQuery("SELECT distinct p_name,p_price FROM products order by Id desc",new String[]{});
这对我有用!!!
答案 6 :(得分：2)
你可以用这个
来做Cursor cursor = database.query(
TABLE_NAME,
YOUR_COLUMNS, null, null, null, null, COLUMN_INTEREST+" DESC");
答案 7 :(得分：2)
SQLite ORDER BY子句用于根据一列或多列以升序或降序对数据进行排序。 游标c = scoreDb.query（DATABASE_TABLE，rank，null，null，null，null，yourColumn +“DESC”）;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(
TABLE_NAME,
rank,
null,
null,
null,
null,
COLUMN + " DESC",
null);
答案 8 :(得分：1)
我们还有一个选项可以通过
进行订购public Cursor getlistbyrank(String rank) {
try {
//This can be used
return db.`query("tablename", null, null, null, null, null, rank +"DESC",null );
OR
return db.rawQuery("SELECT * FROM table order by rank", null);
} catch (SQLException sqle) {
Log.e("Exception on query:-", "" + sqle.getMessage());
return null;
}
}
您可以使用这两种方法进行订购
答案 9 :(得分：0)
关于有效的方法。您可以使用CursorLoader。例如，我包括了我的行动。您必须为您的数据库实现ContentProvider。 https://developer.android.com/reference/android/content/ContentProvider.html
如果您实施此功能，您将非常高效地称呼数据库。
public class LoadEntitiesActionImp implements LoaderManager.LoaderCallbacks<Cursor> {
public interface OnLoadEntities {
void onSuccessLoadEntities(List<Entities> entitiesList);
}
private OnLoadEntities onLoadEntities;
private final Context context;
private final LoaderManager loaderManager;
public LoadEntitiesActionImp(Context context, LoaderManager loaderManager) {
this.context = context;
this.loaderManager = loaderManager;
}
public void setCallback(OnLoadEntities onLoadEntities) {
this.onLoadEntities = onLoadEntities;
}
public void loadEntities() {
loaderManager.initLoader(LOADER_ID, null, this);
}
@Override
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
return new CursorLoader(context, YOUR_URI, null, YOUR_SELECTION, YOUR_ARGUMENTS_FOR_SELECTION, YOUR_SORT_ORDER);
}
@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
}
@Override
public void onLoaderReset(Loader<Cursor> loader) {
}
答案 10 :(得分：0)
private String USER_ID = "user_id";
private String REMEMBER_UN = "remember_un";
private String REMEMBER_PWD = "remember_pwd";
private String HEAD_URL = "head_url";
private String USER_NAME = "user_name";
private String USER_PPU = "user_ppu";
private String CURRENT_TIME = "current_time";
Cursor c = db.rawQuery("SELECT * FROM " + TABLE +" ORDER BY " + CURRENT_TIME + " DESC",null);
每当我更新表格时，我都会更新CURRENT_TIME以进行排序。 但我发现它不起作用。结果没有按照我想要的方式排序。 最后，我发现，列＃34; current_time＆＃34;是sqlite的默认行。 解决方案是，重命名列＆＃34; cur_time＆＃34;而不是＆＃34; current_time＆＃34;。