在删除表之前打开数据库...

Question

我试图在SQLiteOpenHelper的onUpgrade（）方法中删除一个表。我得到一个奇怪的错误＆＃34;没有这样的表＆＃34;在查询中： DROP TABLE IF EXISTS certification_categories。

代码是：

private static final String DROP_CERTIFICATION_CATEGORIES_TABLE = "DROP TABLE IF EXISTS certification_categories";
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
     db.execSQL(DROP_CERTIFICATION_CATEGORIES_TABLE);      
}

并且堆栈跟踪是：

android.database.sqlite.SQLiteException: no such table: main.Auction (code 1): , while compiling: DROP TABLE IF EXISTS certification_categories
                                                                            at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
                                                                            at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
                                                                            at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
                                                                            at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
                                                                            at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
                                                                            at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:31)
                                                                            at android.database.sqlite.SQLiteDatabase.executeSql(SQLiteDatabase.java:1677)
                                                                            at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1608)
                                                                            at com.db.DataBaseHelper.recreate(DataBaseHelper.java:135)
                                                                            at com.db.DataBaseHelper.onDowngrade(DataBaseHelper.java:125)
                                                                            at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:254)
                                                                            at android.database.sqlite.SQLiteOpenHelper.getReadableDatabase(SQLiteOpenHelper.java:187)
                                                                            at com.dao.SyncProgressDao.getUnfinishedAuctionIds(SyncProgressDao.java:45)
                                                                            at com.service.SyncProgressService.getUnfinishedAuctionIds(SyncProgressService.java:69)
                                                                            at com.background.AuctionSync.syncUnfinished(AuctionSync.java:102)
                                                                            at com.background.AuctionSync.onHandleIntent(AuctionSync.java:97)
                                                                            at android.app.IntentService$ServiceHandler.handleMessage(IntentService.java:68)
                                                                            at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                            at android.os.Looper.loop(Looper.java:154)
                                                                            at android.os.HandlerThread.run(HandlerThread.java:61)

Answer 1

在删除表之前打开数据库...

private static final String DROP_CERTIFICATION_CATEGORIES_TABLE = "DROP TABLE IF EXISTS certification_categories";
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
         db = openorCreateDatabase("DB_NAME",this.MODE_PRIVATE,null);
         db.execSQL(DROP_CERTIFICATION_CATEGORIES_TABLE);      
}

Answer 2

我弄清楚造成这种情况的原因。另一个表与certification_categories表有一个外键关联。

因此，首先删除该表然后删除certification_categories解决了这个问题。

然而，他们可能会标记出相应的错误，而不是“没有这样的表格＆＃39;使事情变得更容易。

DROP TABLE如果EXISTS在SQLite android中不起作用

2 个答案:

在删除表之前打开数据库...