How To Delete All Table Records In Sqlite?

I get JSON value from a server and save the data into a database in Sqlite in Android, I create a database and a table with SQLiteOpenHelper class: public class ActivityTableDBOpen

Solution 1:

You should first initialize you SQLiteDatabase, so convert this:

SQLiteDatabase database;
database.delete(ActivityTableDBOpenHelper.ACTIVITY_TABLE,null,null); 

to this:

SQLiteDatabasedatabase=newSQLiteDatabase(this); // or dbHelper.getWritableDatabase(); if you have a dbHelper
database.delete(ActivityTableDBOpenHelper.ACTIVITY_TABLE,null,null);

Else the database object is null and you get the error. Here you could find a whole example for all operations http://www.vogella.com/tutorials/AndroidSQLite/article.html

Solution 2:

db.execSQL("delete from "+ TABLE_NAME);

Solution 3:

The problem with your call

SQLiteDatabase database;
database.delete(ActivityTableDBOpenHelper.ACTIVITY_TABLE,null,null); 

is that your database-object is null. Call SQLiteDatabase db = getWritableDatabase() and proceed.

To delete information from your database or specific tables you can also use basic SQL-Queries: http://www.w3schools.com/sql/sql_delete.asp

db.rawQuery("DELETE FROM " + table + " WHERE " + args);

Solution 4:

I found where I was wrong :D

thanks to @Gabriella Angelova

I have to initializing SQLiteDatabase and SQLiteOpenHelper

publicclassActivityTableActivityextendsActionBarActivity {

    SQLiteDatabase database;
    ActivityTableDBOpenHelper dbOpenHelper;

    @OverrideprotectedvoidonCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_activity_table);

        dbOpenHelper = newActivityTableDBOpenHelper(this);
        database = dbOpenHelper.getWritableDatabase();

        btnDeleteATData = (Button) findViewById(R.id.btnDeleteATData);

        dataSource = newActivityTableDataSource(this);
        dataSource.open();

        btnDeleteATData.setOnClickListener(newView.OnClickListener() {
            @OverridepublicvoidonClick(View v) {        
                database.delete(ActivityTableDBOpenHelper.ACTIVITY_TABLE, null, null);
            }
        });

    }

Solution 5:

//ourDb ->SqliteDatabase object//TABLE_NAME -> publicvoiddeleteDatafromAllTables() {
    ourDb.execSQL("delete from " + TABLE_NAME);
}