tharindlaksh tharindlaksh - 1 month ago 12
Android Question

Remove all table rows from SQLite database table

I want to remove all rows that i entered from my SQLite database table. The table name is tbltask.
I tried to drop the table and delete * from table, but those are giving me runtime errors.
I want to trigger this event in Button OnClickListner event.

Following code is what I tried:

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


LogCat:

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}


This is the LogCat output I get for following query:

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

Answer

Just do:

db.delete(DATABASE_TABLE, null, null);

Note that using rawQuery should work, but can be a potential security risk.

EDIT:

About the problem you have when you use

db.execSQL

Read the documentation, it says you should not use execSQL with INSERT, DELETE, UPDATE or SELECT

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