以下语句cursor.moveToNext()始终为false.我希望循环执行一次.我已经测试过查询实际返回的数据.
有谁知道是什么事吗？
String query ="SELECT(SELECT COUNT(*) FROM Table1) as count1,(SELECT COUNT(*) FROM Table2) as count2;";
Cursor mCursor = mDb.rawQuery(query,null);
if (mCursor != null) {
mCursor.moveToFirst();
}
while (cursor.moveToNext()) { //<---------------return false here???
String result_0=cursor.getString(0);
}
解决方法
我知道你已经解决了你的问题,但这是对发生的事情的一个演练：
Cursor mCursor = mDb.rawQuery(query,null);
// At this point mCursor is positioned at just before the first record.
if (mCursor != null) {
mCursor.moveToFirst();
// mCursor is now pointing at the first (and only) record
}
while (mCursor.moveToNext()) {
String result_0=cursor.getString(0);
}
// The loop above was skipped because `.moveToNext()` caused mCursor
// to move past the last record.
因此,在您只需要一条记录的情况下,您只需要mCursor.moveToFirst()或您的mCursor.moveToNext().
