现有用户信息表userinfo,表结构如下:id integer 主键,自增长;uname text 用户名;password text 密码。如果想查询用户名为的用户信息,下面方法正确的是() A. private void select(SQLiteDatabase db){ ... String sql="select * from where uname=''"; Cursor cursor = db.rawQuery(sql,null); ... } B. private void select(SQLiteDatabase db){ ... String sql="select * from where uname=?"; Cursor cursor = db.rawQuery(sql,new String[]{""}); ... } C. private void select(SQLiteDatabase db){ ... Cursor cursor = db.query("userinfo",new String[]{"id","uname","password"},"uname=?",new String[]{""},null,null,null,null); ... } D. private void select(SQLiteDatabase db){ ... Cursor cursor = db.query("userinfo",new String[]{"id","uname","password"},"uname=?",null,null,null,null,new String[]{""}); ... }