在android中重命名SQL数据库
当引用数据库表时，我通常使用如下语法：my_database_name.my_table_name
我试图在 Android 中执行相同的操作，但无法理解如何命名数据库。
您会像在 Sqlite3 客户端中一样执行此 SQL 吗？即，
ATTACH "my_database_file" AS my_database_name;
这是我在 onCreate 方法中尝试的内容：
db.execSQL("Attach 'hq_db' AS hq_db;");
但我收到此错误：
04-05 11:13:35.676: ERROR/AndroidRuntime(860): Caused by: android.database.sqlite.SQLiteException: cannot ATTACH database within transaction: Attach 'hq_db' AS hq_db;
如何在事务之外在 Android 上执行 SQL 语句以使其工作？
编辑：它也可能与超类构造函数有关，尽管超类构造函数字符串设置文件名（工作正常）并且似乎没有其他内容：
private class databaseOpenHelper extends SQLiteOpenHelper {
public q_player_databaseOpenHelper() {
super(MyApp.getContext(), "my_db_file", null, 1);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("Attach 'my_db_file' AS my_db_name;");
db.execSQL("PRAGMA foreign_keys=ON;");
}
注意：我已经删除了这段代码，因此它适合我的问题
When referring to database tables I usually use syntax like this: my_database_name.my_table_name
I am trying to do the same in Android but am having trouble understanding how to name a database.
Would you just execute this SQL as you would in the Sqlite3 client? i.e.
ATTACH "my_database_file" AS my_database_name;
Here is what I tried in my onCreate method:
db.execSQL("Attach 'hq_db' AS hq_db;");
but I'm getting this error:
04-05 11:13:35.676: ERROR/AndroidRuntime(860): Caused by: android.database.sqlite.SQLiteException: cannot ATTACH database within transaction: Attach 'hq_db' AS hq_db;
How do I execute SQL statements on Android outside of a transaction to make this work?
Edit: It might also have something to so with the superclass constuctor, though the super class constructor string sets the file name (which is working properly) and it seems nothing else:
private class databaseOpenHelper extends SQLiteOpenHelper {
public q_player_databaseOpenHelper() {
super(MyApp.getContext(), "my_db_file", null, 1);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("Attach 'my_db_file' AS my_db_name;");
db.execSQL("PRAGMA foreign_keys=ON;");
}
Note: I have stripped this code down so it would fit my problem
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在开始任何类型的事务之前，您需要调用 db.execSQL("ATTACH 'hq_db' AS hq_db;");。先做附件，再开始交易。
您是否在尝试附加其他数据库之前调用
beginTransaction或执行开始事务的 SQL？You need to call
db.execSQL("ATTACH 'hq_db' AS hq_db;");before you start any kind of transaction. Do the attachment first, and then start the transaction.Are you calling
beginTransactionor executing SQL which begins a transaction before trying to attach your other database?您可能正在使用 AutoCommit=0 创建数据库。这会将您置于一个事务中，这样就不需要在每次插入后写入数据库文件。但这也意味着您无法附加到另一个数据库。创建数据库，设置 AutoCommit=1，ATTACH，然后设置 AutoCommit=0。
You're probably creating the database with AutoCommit=0. This puts you in a transaction so that it doesn't need to write to the database file after every INSERT. But it also means you can't ATTACH to another database. Create the DB, set AutoCommit=1, ATTACH, then set AutoCommit=0.