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这就是我创建数据库的方式
private static class DatabaseHelper extends sqliteOpenHelper { DatabaseHelper(Context context) { super(context,DATABASE_NAME,null,DATABASE_VERSION); } @Override public void onCreate(sqliteDatabase db) { createTables(db); } @Override public void onUpgrade(sqliteDatabase db,int oldVersion,int newVersion) { Log.w("CalendarDB","Upgrading database from version " + oldVersion + " to " + newVersion + ",which will destroy all old data"); db.execsql("drop table IF EXISTS Events_Table"); onCreate(db); } private void createTables(sqliteDatabase db){ db.execsql("create table " + EVENTS_TABLE + "(" + ID + " INTEGER PRIMary key autoincrement," + EVENT + " TEXT," + LOCATION + " TEXT," + DESCRIPTION + " TEXT," + DATE + " TEXT," + START + " LONG," + END + " TEXT," + REAL_START_TIME + " TEXT," + REAL_END_TIME + " TEXT," + COLOR + " TEXT," + BLINK + " TEXT," + VIBRATE + " TEXT," + RING_TONE_PATH + " TEXT," + ICON + " TEXT," + REMINDERS + " TEXT," + START_WITH_REMINDER + " TEXT," + CALENDAR_ID + " TEXT," + EVENT_ID + " TEXT);"); } }
还有什么我需要做的才能让onupdate被调用吗？我试过跟随this answer,但仍然没有结果
Rembember
这仅在您调用getWritableDatabase()时有效,否则将无法升级.如果更改版本并调用getReadableDatabase,它将显示异常
throw new sqliteException("Can't upgrade read-only database from version " + db.getVersion() + " to " + mNewVersion + ": " + path);
但为什么？
你看到当你拨打getWritableDatabase代码检查时,版本是相同的：
if (version != mNewVersion) { db.begintransaction(); try { if (version == 0) { onCreate(db); } else { if (version > mNewVersion) { onDowngrade(db,version,mNewVersion); } else { onUpgrade(db,mNewVersion); } } db.setVersion(mNewVersion); db.settransactionsuccessful(); } finally { db.endtransaction(); } }
更新
事实证明它应该与getReadableDatabase()一起使用,因为在代码中你总是得到一个WrittableDatabase.所以它应该适用于这两种方法,这里是getReadableDatabase()的文档：
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