SQLite db重复值Android

Question

我在我的应用程序中使用了spinner，它从 SQLite 数据库中获取值。问题是每次我从 Eclipse 运行应用程序时，值都会一次又一次地加载。所以如果我第一次在spinner 中有 5 个值，第二次我有 10 个值，然后是 15，然后是 20 等等。我该如何解决这个问题？

这是数据库部分：

在onCreate：

createTable();
        insertIntoTable();

        ArrayList<String> my_array = new ArrayList<String>();
        my_array = getTableValues();

        My_spinner = (Spinner) findViewById(R.id.scelte);
        My_spinner.setOnItemSelectedListener(this);
        ArrayAdapter my_Adapter = new ArrayAdapter(this, R.layout.spinner_row, my_array);
        My_spinner.setAdapter(my_Adapter);

然后：

// CREATE TABLE IF NOT EXISTS
    public void createTable() {
        try {
            mydb = openOrCreateDatabase(DBNAME, Context.MODE_PRIVATE, null);
            mydb.execSQL("CREATE TABLE IF  NOT EXISTS " + TABLE
                    + " (ID INTEGER PRIMARY KEY, NAME TEXT, PLACE TEXT);");
            mydb.close();
        } catch (Exception e) {
            Toast.makeText(getApplicationContext(), "Errore durante la creazione della tabella",
                    Toast.LENGTH_LONG);
        }
    }

    // THIS FUNCTION INSERTS DATA TO THE DATABASE
    public void insertIntoTable() {
        try {
            mydb = openOrCreateDatabase(DBNAME, Context.MODE_PRIVATE, null);
            mydb.execSQL("INSERT INTO " + TABLE
                    + "(NAME, PLACE) VALUES('Cibo e Bevande','cibo')");
            mydb.execSQL("INSERT INTO " + TABLE
                    + "(NAME, PLACE) VALUES('Trasporti','trasporti')");
            mydb.execSQL("INSERT INTO " + TABLE
                    + "(NAME, PLACE) VALUES('Svago','svago')");
            mydb.execSQL("INSERT INTO " + TABLE
                    + "(NAME, PLACE) VALUES('Acquisti vari','acquisti')");
            mydb.execSQL("INSERT INTO " + TABLE
                    + "(NAME, PLACE) VALUES('Sanità','sanità')");
            mydb.execSQL("INSERT INTO " + TABLE
                    + "(NAME, PLACE) VALUES('Altro','altro')");
            mydb.close();


        } catch (Exception e) {
            Toast.makeText(getApplicationContext(),
                    "Error in inserting into table", Toast.LENGTH_LONG);
        }
    }

    // THIS FUNCTION SHOWS DATA FROM THE DATABASE
    public ArrayList<String> getTableValues() {

        ArrayList<String> my_array = new ArrayList<String>();
        try {
            mydb = openOrCreateDatabase(DBNAME, Context.MODE_PRIVATE, null);
            Cursor allrows = mydb.rawQuery("SELECT * FROM " + TABLE, null);
            System.out.println("COUNT : " + allrows.getCount());

            if (allrows.moveToFirst()) {
                do {

                    String ID = allrows.getString(0);
                    String NAME = allrows.getString(1);
                    String PLACE = allrows.getString(2);
                    my_array.add(NAME);


                } while (allrows.moveToNext());
            }
            allrows.close();
            mydb.close();
        } catch (Exception e) {
            Toast.makeText(getApplicationContext(), "Errore.",
                    Toast.LENGTH_LONG);
        }
        return my_array;

    }

    @Override
    public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2,
            long arg3) {
        // TODO Auto-generated method stub
        String selecteditem = My_spinner.getSelectedItem().toString();
        TextView categorietext = (TextView) findViewById(R.id.sceltelabel);
        categorietext.setText(selecteditem);
    }

    @Override
    public void onNothingSelected(AdapterView<?> arg0) {
        // TODO Auto-generated method stub

    }

Answer 1

你运行这个

insertIntoTable();

每次在onCreate 中都会添加越来越多的数据。

您应该使用扩展SQLiteOpenHelper 类并使用onCreate 方法来创建您的数据库和初始化表。见Android developer reference。

Answer 2

每次您打开活动时，onCreate 活动方法都会被调用，而在您的 onCreate 方法中，您将调用 insertIntoTable();，它每次都会插入新记录。

Answer 3

每次运行您的应用程序时，您都会调用insertintotable() 方法，所以它正在发生

解决这个问题：

检查表是否为空。如果为空则调用insertintotable()方法否则不要

Answer 4

每次运行应用程序时，都会调用onCreate()，因此也会调用insertIntoTable()。您必须在插入数据之前添加检查。其中一种方法是在插入数据之前检查数据库是否为空。

public void insertIntoTable() {
    try {
        mydb = openOrCreateDatabase(DBNAME, Context.MODE_PRIVATE, null);
        Cursor c = mydb.query(TABLE, null, null, null, null, null, null);
        if (c == null || c.getCount() == 0) {
            mydb.execSQL("INSERT INTO " + TABLE
                + "(NAME, PLACE) VALUES('Cibo e Bevande','cibo')");
            mydb.execSQL("INSERT INTO " + TABLE
            + "(NAME, PLACE) VALUES('Trasporti','trasporti')");
            mydb.execSQL("INSERT INTO " + TABLE
            + "(NAME, PLACE) VALUES('Svago','svago')");
            mydb.execSQL("INSERT INTO " + TABLE
            + "(NAME, PLACE) VALUES('Acquisti vari','acquisti')");
            mydb.execSQL("INSERT INTO " + TABLE
            + "(NAME, PLACE) VALUES('Sanità','sanità')");
            mydb.execSQL("INSERT INTO " + TABLE
            + "(NAME, PLACE) VALUES('Altro','altro')");
            mydb.close();
        }
        c.close();
    } catch (Exception e) {
        Toast.makeText(getApplicationContext(),
            "Error in inserting into table", Toast.LENGTH_LONG);
    }
}