在Android的依附SQLite数据库用SQLiteOpenHelper [英] ATTACH sqlite database in Android with SQLiteOpenHelper

问题描述

我在创建引用键在另一个数据库中的数据库的过程。从本质上讲，我有我想保持分开的，这将改变数据的导入，但如果可能的话，我想通过一个外部关键字引用的其他键。所以，据我所知，我需要首先将数据库来实现这一目标。这里的德相关code到目前为止：

I'm in the process of creating a database that references keys in another database. Essentially, I have an import of data that I want to keep separate from one that will change, but if possible, I would like to reference the other keys via a FOREIGN KEY. So far as I know, I need to attach the database first to make that happen. Here's teh relevant code so far:

public class LogDatabaseHelper extends SQLiteOpenHelper {

    private static final String DATABASE_NAME = "log.db";
    private static final int DATABASE_VERSION = 1;
    private String namesDb;

    public LogDatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        namesDb=getNamesDbPath();

    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("ATTACH DATABASE ? AS names",new String[]{namesDb});
        StringBuilder query=new StringBuilder();
        query.append("CREATE TABLE log (");
    }
}

不过，这似乎并没有工作，因为我得到了以下错误：

However, this doesn't seem to work, as I'm getting the following error:

11-21 17:35:58.176: E/SQLiteLog(9984): (1) statement aborts at 5: [ATTACH DATABASE ? AS names] cannot ATTACH database within transaction
11-21 17:35:58.176: D/AndroidRuntime(9984): Shutting down VM
11-21 17:35:58.176: W/dalvikvm(9984): threadid=1: thread exiting with uncaught exception (group=0x41a21700)
11-21 17:35:58.191: E/AndroidRuntime(9984): FATAL EXCEPTION: main
11-21 17:35:58.191: E/AndroidRuntime(9984): android.database.sqlite.SQLiteException: cannot ATTACH database within transaction (code 1)
11-21 17:35:58.191: E/AndroidRuntime(9984):     at android.database.sqlite.SQLiteConnection.nativeExecuteForChangedRowCount(Native Method)
11-21 17:35:58.191: E/AndroidRuntime(9984):     at android.database.sqlite.SQLiteConnection.executeForChangedRowCount(SQLiteConnection.java:734)
11-21 17:35:58.191: E/AndroidRuntime(9984):     at android.database.sqlite.SQLiteSession.executeForChangedRowCount(SQLiteSession.java:754)
11-21 17:35:58.191: E/AndroidRuntime(9984):     at android.database.sqlite.SQLiteStatement.executeUpdateDelete(SQLiteStatement.java:64)
11-21 17:35:58.191: E/AndroidRuntime(9984):     at android.database.sqlite.SQLiteDatabase.executeSql(SQLiteDatabase.java:1674)
11-21 17:35:58.191: E/AndroidRuntime(9984):     at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1603)
11-21 17:35:58.191: E/AndroidRuntime(9984):     at com.kd7uiy.hamfinder.LogDatabaseHelper.onCreate(LogDatabaseHelper.java:27)
11-21 17:35:58.191: E/AndroidRuntime(9984):     at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:252)
11-21 17:35:58.191: E/AndroidRuntime(9984):     at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:164)

我怎样才能使这项工作？

How can I make this work?

推荐答案

我想出了一个办法，使其工作，我不是特别自豪，但它的工作。如果连接数据库时，你不能在一个事务中，那么首先结束交易。

I figured out a way to make it work, that I'm not particularly proud of, but it does the job. If you can't be in a transaction when attaching a database, then end the transaction first.

db.setTransactionSuccessful();
db.endTransaction();
db.execSQL("ATTACH DATABASE ? AS names",new String[]{namesDb});
db.beginTransaction();

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