SQLite添加列,保留数据

我有一个数据库有4列:

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

现在我想添加另一列,但保留已经在数据库中的行。 我应该怎么做? 我找不到任何有用的参考。

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

编辑

我已经修改我的onCreate到:

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

和我的升级到:

 @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); } 

但是,现在我得到这个堆栈跟踪:

 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 

Solutions Collecting From Web of "SQLite添加列,保留数据"

请参阅此页面以获取在表格上创build新列的语法。 基本上是这样的:

 ALTER TABLE mytable ADD COLUMN mycolumn TEXT 

在你的onUpgrade方法中,它看起来像这样:

 @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); } 

一个更好的方法

 @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"); } } 

让我们说情况1,你升级到数据库版本2.你创build了一个新的表,但忘记了myNewColumn你会看到情况2.这将做的是,如果你改变数据库版本为3,情况2将得到运行,如果其从2升级到3。

我没有使用过android,但是sqlite提供了像大多数SQL实现一样的“alter table”:

SQLite的改变表