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SQLite的加列，保持數據

2011-10-01 15 views
27

我有4列的數據庫：SQLite的加列，保持數據

@Override 
public void onCreate(SQLiteDatabase database) { 
     database.execSQL("CREATE TABLE " + DATABASENAME + " (name TEXT, latitude REAL, longitude REAL, country TEXT);"); 
}

現在我想補充另一列，但記住這是已經在數據庫中的行。我應該怎麼做？我找不到任何有用的參考資料。

@Override 
public void onUpgrade(SQLiteDatabase db, int arg1, int arg2) { 
    //What to do here? 
}

編輯

我已經修改了我的onCreate到：

@Override 
public void onCreate(SQLiteDatabase database) { 
    database.execSQL("CREATE TABLE " + DATABASENAME + " (name TEXT, latitude REAL, longitude REAL, country TEXT, code TEXT);"); 
}

和我onUpgrade到：

@Override 
public void onUpgrade(SQLiteDatabase db, int arg1, int arg2) { 
    Logger.log("Updating userstations database from " + arg1 + " to " + arg2 + "."); 
    if (arg1 == 2 && arg2 == 3) { 
     db.execSQL("ALTER TABLE " + DATABASENAME + " ADD COLUMN code TEXT;"); 
    } else if(arg1 == 1){ 
     db.execSQL("DROP TABLE IF EXISTS " + DATABASENAME); 
    } 
    onCreate(db); 
}

不過，現在我得到這個堆棧跟蹤：

10-01 21:24:19.581: ERROR/Database(21434): Failure 1 (table userstations already exists) on 0x19c378 when preparing 'CREATE TABLE userstations (name TEXT, latitude REAL, longitude REAL, country TEXT, code TEXT);'. 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434): Couldn't open userstations for writing (will try read-only): 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434): android.database.sqlite.SQLiteException: table userstations already exists: CREATE TABLE userstations (name TEXT, latitude REAL, longitude REAL, country TEXT, code TEXT); 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.database.sqlite.SQLiteDatabase.native_execSQL(Native Method) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1763) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at com.myapp.myapp.databases.UserStationsOpenHelper.onCreate(UserStationsOpenHelper.java:25) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at com.myapp.myapp.databases.UserStationsOpenHelper.onUpgrade(UserStationsOpenHelper.java:36) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:132) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.database.sqlite.SQLiteOpenHelper.getReadableDatabase(SQLiteOpenHelper.java:187) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at com.myapp.myapp.databases.UserStationsOpenHelper.getStations(UserStationsOpenHelper.java:43) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at com.myapp.myapp.Data.readUserStations(Data.java:369) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at com.myapp.myapp.Data.getUserStations(Data.java:210) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at com.myapp.myapp.stationstab.StationsActivity.newStations(StationsActivity.java:190) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at com.myapp.myapp.stationstab.StationsActivity.refresh(StationsActivity.java:129) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at com.myapp.myapp.stationstab.StationsActivity.onCreate(StationsActivity.java:108) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1722) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.app.ActivityThread.startActivityNow(ActivityThread.java:1598) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.app.LocalActivityManager.moveToState(LocalActivityManager.java:127) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.app.LocalActivityManager.startActivity(LocalActivityManager.java:339) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at com.myapp.myapp.stationstab.StationsActivityGroup.onCreate(StationsActivityGroup.java:38) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1722) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.app.ActivityThread.startActivityNow(ActivityThread.java:1598) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.app.LocalActivityManager.moveToState(LocalActivityManager.java:127) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.app.LocalActivityManager.startActivity(LocalActivityManager.java:339) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.widget.TabHost$IntentContentStrategy.getContentView(TabHost.java:654) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.widget.TabHost.setCurrentTab(TabHost.java:326) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.widget.TabHost.addTab(TabHost.java:216) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at com.myapp.myapp.TreinVerkeer.setupTab(TreinVerkeer.java:131) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at com.myapp.myapp.TreinVerkeer.initTabs(TreinVerkeer.java:108) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at com.myapp.myapp.TreinVerkeer.onCreate(TreinVerkeer.java:62) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1722) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1784) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.app.ActivityThread.access$1500(ActivityThread.java:123) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:939) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.os.Handler.dispatchMessage(Handler.java:99) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.os.Looper.loop(Looper.java:123) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at android.app.ActivityThread.main(ActivityThread.java:3835) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at java.lang.reflect.Method.invokeNative(Native Method) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at java.lang.reflect.Method.invoke(Method.java:507) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599) 
10-01 21:24:19.611: ERROR/SQLiteOpenHelper(21434):  at dalvik.system.NativeStart.main(Native Method) 
10-01 21:24:19.621: DEBUG/AndroidRuntime(21434): Shutting down VM 
10-01 21:24:19.621: WARN/dalvikvm(21434): threadid=1: thread exiting with uncaught exception (group=0x4018a560) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434): FATAL EXCEPTION: main 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.myapp.myapp/com.myapp.myapp.TreinVerkeer}: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.myapp.myapp/com.myapp.myapp.stationstab.StationsActivityGroup}: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.myapp.myapp/com.myapp.myapp.stationstab.StationsActivity}: android.database.sqlite.SQLiteException: Can't upgrade read-only database from version 2 to 3: /data/data/com.myapp.myapp/databases/userstations 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1768) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1784) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.app.ActivityThread.access$1500(ActivityThread.java:123) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:939) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.os.Handler.dispatchMessage(Handler.java:99) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.os.Looper.loop(Looper.java:123) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.app.ActivityThread.main(ActivityThread.java:3835) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at java.lang.reflect.Method.invokeNative(Native Method) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at java.lang.reflect.Method.invoke(Method.java:507) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at dalvik.system.NativeStart.main(Native Method) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434): Caused by: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.myapp.myapp/com.myapp.myapp.stationstab.StationsActivityGroup}: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.myapp.myapp/com.myapp.myapp.stationstab.StationsActivity}: android.database.sqlite.SQLiteException: Can't upgrade read-only database from version 2 to 3: /data/data/com.myapp.myapp/databases/userstations 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1768) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.app.ActivityThread.startActivityNow(ActivityThread.java:1598) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.app.LocalActivityManager.moveToState(LocalActivityManager.java:127) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.app.LocalActivityManager.startActivity(LocalActivityManager.java:339) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.widget.TabHost$IntentContentStrategy.getContentView(TabHost.java:654) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.widget.TabHost.setCurrentTab(TabHost.java:326) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.widget.TabHost.addTab(TabHost.java:216) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at com.myapp.myapp.TreinVerkeer.setupTab(TreinVerkeer.java:131) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at com.myapp.myapp.TreinVerkeer.initTabs(TreinVerkeer.java:108) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at com.myapp.myapp.TreinVerkeer.onCreate(TreinVerkeer.java:62) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1722) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  ... 11 more 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434): Caused by: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.myapp.myapp/com.myapp.myapp.stationstab.StationsActivity}: android.database.sqlite.SQLiteException: Can't upgrade read-only database from version 2 to 3: /data/data/com.myapp.myapp/databases/userstations 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1768) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.app.ActivityThread.startActivityNow(ActivityThread.java:1598) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.app.LocalActivityManager.moveToState(LocalActivityManager.java:127) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.app.LocalActivityManager.startActivity(LocalActivityManager.java:339) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at com.myapp.myapp.stationstab.StationsActivityGroup.onCreate(StationsActivityGroup.java:38) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1722) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  ... 22 more 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434): Caused by: android.database.sqlite.SQLiteException: Can't upgrade read-only database from version 2 to 3: /data/data/com.myapp.myapp/databases/userstations 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at android.database.sqlite.SQLiteOpenHelper.getReadableDatabase(SQLiteOpenHelper.java:199) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at com.myapp.myapp.databases.UserStationsOpenHelper.getStations(UserStationsOpenHelper.java:43) 
10-01 21:24:19.641: ERROR/AndroidRuntime(21434):  at com.myapp.myapp

來源

2011-10-01 nhaarman

回答

48

請參閱this頁的語法在表上創建一個新列。基本上，它是：

ALTER TABLE mytable ADD COLUMN mycolumn TEXT

在你onUpgrade方法，它會是這個樣子：

@Override 
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
    String upgradeQuery = "ALTER TABLE mytable ADD COLUMN mycolumn TEXT"; 
    if (oldVersion == 1 && newVersion == 2) 
     db.execSQL(upgradeQuery); 
}

來源

2011-10-01 18:32:22 Jack

+0

請參閱我的編輯 – nhaarman

+1

爲什麼你事後調用onCreate（）？升級意味着已經調用了onCreate（）（意味着已經創建了tables/db）。這個問題在例外中詳細說明（甚至直到行號 - onCreate（）中的第25行）。您正試圖創建一個已經存在的表格。 – Jack

+0

啊，好的。但是我有從版本1更新後刪除數據庫的行，我需要調用onCreate嗎？ – nhaarman

2

我還沒有與Android合作，但源碼提供「變更表」，因爲大多數SQL實現的功能：

SQLite alter table

來源

2011-10-01 18:29:56

+0

ALTER TABLE MyTable ADD COLUMN MyNewCol TEXT; –

6

一個更好的辦法

@Override 
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
    switch (oldVersion) { 
     case 1: 
      db.execSQL(SQL_MY_TABLE); 


     case 2: 
      db.execSQL("ALTER TABLE myTable ADD COLUMN myNewColumn TEXT"); 

    } 
}

允許的情況下，1說，你升級到數據庫版本2.你創建了一個新表，但忘記了你將在情況2中看到的myNewColumn。這將做什麼，如果你改變數據庫版本爲3，情況2將會運行，如果它的從2升級到3.

來源

2014-05-15 01:23:16 Codeversed

+0

在版本3中，不區分第二個查詢，冗餘在case3中查詢 –

+0

這在onUpgrade上顯示舊版本是版本2，所以新版本將會是版本3並且它會運行代碼這個代碼是正確的並且可以工作 – Codeversed

+2

我看到這個代碼的唯一問題是你應該從switch語句中刪除所有中斷（並確保所有的case都是升序），這樣oldVersion case下面的所有case也會被執行。 – TheIT

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