从SQLite数据库表中删除所有表行

Question

我想删除我从SQLite数据库表中输入的所有行.表名是tbltask.我试图删除表并从表中删除*,但那些给了我运行时错误.我想在Button OnClickListner事件中触发此事件.

以下代码是我尝试的:

String delete = "DELETE FROM "+DATABASE_TABLE;
db.rawQuery(delete, null);
db.delete(DATABASE_TABLE, null, null);

logcat的:

11-15 17:45:04.660: DEBUG/AndroidRuntime(300): Shutting down VM
11-15 17:45:04.660: WARN/dalvikvm(300): threadid=1: thread exiting with uncaught exception (group=0x4001d800) 
11-15 17:45:04.710: ERROR/AndroidRuntime(300): FATAL EXCEPTION: main 
11-15 17:45:04.710: ERROR/AndroidRuntime(300): java.lang.NullPointerException 
11-15 17:45:04.710: ERROR/AndroidRuntime(300): at database.com.android.DatabaseAccess.drop(DatabaseAccess.java:258) 
11-15 17:45:04.710: ERROR/AndroidRuntime(300): at com.android.ExtraActivity$3$1.onClick(ExtraActivity.java:61) 
11-15 17:45:04.710: ERROR/AndroidRuntime(300): at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:158) 
11-15 17:45:04.710: ERROR/AndroidRuntime(300): at android.os.Handler.dispatchMessage(Handler.java:99) 
11-15 17:45:04.710: ERROR/AndroidRuntime(300): at android.os.Looper.loop(Looper.java:123) 
11-15 17:45:04.710: ERROR/AndroidRuntime(300): at android.app.ActivityThread.main(ActivityThread.java:4627) 
11-15 17:45:04.710: ERROR/AndroidRuntime(300): at java.lang.reflect.Method.invokeNative(Native Method) 
11-15 17:45:04.710: ERROR/AndroidRuntime(300): at java.lang.reflect.Method.invoke(Method.java:521) 
11-15 17:45:04.710: ERROR/AndroidRuntime(300): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 
11-15 17:45:04.710: ERROR/AndroidRuntime(300): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 
11-15 17:45:04.710: ERROR/AndroidRuntime(300): at dalvik.system.NativeStart.main(Native Method) 
11-15 17:45:04.781: WARN/ActivityManager(58): Force finishing activity com.android/.ExtraActivity 
11-15 17:45:05.320: WARN/ActivityManager(58): Activity pause timeout for HistoryRecord{45061a70 com.android/.ExtraActivity} 
11-15 17:45:14.857: WARN/ActivityManager(58): Launch timeout has expired, giving up wake lock! 
11-15 17:45:15.402: WARN/ActivityManager(58): Activity idle timeout for HistoryRecord{450141d0 com.android/.WelcomActivity} 
11-15 17:45:20.572: WARN/ActivityManager(58): Activity destroy timeout for HistoryRecord{45061a70 com.android/.ExtraActivity}

这是我获得以下查询的LogCat输出:

        String delete = "DELETE FROM taskTable";
    db.execSQL(delete);

Answer 1

做就是了:

db.delete(DATABASE_TABLE, null, null);

请注意,使用rawQuery应该可行,但可能存在潜在的安全风险.

编辑:

关于您使用时遇到的问题

db.execSQL

阅读文档,它说你不应该使用execSQL与INSERT,DELETE,UPDATE或SELECT