“选择 last_insert_rowid()"总是返回“0" [英] "SELECT last_insert_rowid()" returns always "0"

问题描述

我对last_insert_rowid()"有疑问.

I have a problem with "last_insert_rowid()".

在我的 DB-Helper-Class 中，我正在执行以下操作:

In my DB-Helper-Class I am doing the following:

public int getLastID() {
    final String MY_QUERY = "SELECT last_insert_rowid() FROM "+ DATABASE_TABLE5;
    Cursor cur = mDb.rawQuery(MY_QUERY, null);
    cur.moveToFirst();
    int ID = cur.getInt(0);
    cur.close();
    return ID;
}

但是当我按照我的意图调用它时:

But when I call this in my intent:

int ID = mDbHelper.getLastID(); 
Toast.makeText(this, "LastID: " + ID, Toast.LENGTH_SHORT).show();

我总是返回0".不可能，因为我的数据库中有很多条目，并且自动增量值应该高得多.

I get always "0" back. That can not be, cause I have a lot of entries in my DB and the autoincrement value should be much higher.

我做错了什么?

推荐答案

好的，这是正确的提示 John ;-)

OK, that was the right hint John ;-)

查询应如下所示:

public int getHighestID() {
final String MY_QUERY = "SELECT MAX(_id) FROM " + DATABASE_TABLE5;
Cursor cur = mDb.rawQuery(MY_QUERY, null);
cur.moveToFirst();
int ID = cur.getInt(0);
cur.close();
return ID;
}   

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