Question

我使用this example编写了一些代码，以便在 SQlite 中保存和更新2个长值。我可以创建新行，但我无法更新它。我尽我所能，但我无法更新一行，没有错误只是没有更新行。我正在使用此代码更新一行：

db.updateContact(new Contact(consumed, total));

消耗的和总的是长值。我无法看到任何错误，但更新行仍然无法取得成功。我的构造函数和databesehandler代码如下：

Contaxt.java

public class Contact {

// private variables
int _id;
double _name;
double _phone_number;

// Empty constructor
public Contact() {

}

// constructor
public Contact(int id, double name, double _phone_number) {
    this._id = id;
    this._name = name;
    this._phone_number = _phone_number;
}

// constructor
public Contact(double name, double _phone_number) {
    this._name = name;
    this._phone_number = _phone_number;
}

// getting ID
public int getID() {
    return this._id;
}

// setting id
public void setID(int id) {
    this._id = id;
}

// getting name
public double getName() {
    return this._name;
}

// setting name
public void setName(double name) {
    this._name = name;
}

// getting phone number
public double getPhoneNumber() {
    return this._phone_number;
}

// setting phone number
public void setPhoneNumber(double phone_number) {
    this._phone_number = phone_number;
}

}

DatabeseHandler.java

public class DatabaseHandler extends SQLiteOpenHelper {

    // All Static variables
    // Database Version
    private static final int DATABASE_VERSION = 1;

    // Database Name
    private static final String DATABASE_NAME = "contactsManager";

    // Contacts table name
    private static final String TABLE_CONTACTS = "contacts";

    // Contacts Table Columns names
    private static final String KEY_ID = "id";
    private static final String KEY_NAME = "name";
    private static final String KEY_PH_NO = "phone_number";

    public DatabaseHandler(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    // Creating Tables
    @Override
    public void onCreate(SQLiteDatabase db) {
        String CREATE_CONTACTS_TABLE = "CREATE TABLE " + TABLE_CONTACTS + "(" + KEY_ID
                + " INTEGER PRIMARY KEY AUTOINCREMENT," + KEY_NAME + " TEXT," + KEY_PH_NO + " TEXT" + ")";
        db.execSQL(CREATE_CONTACTS_TABLE);
    }

    // Upgrading database
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // Drop older table if existed
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_CONTACTS);

        // Create tables again
        onCreate(db);
    }

    // Adding new contact
    void addContact(Contact contact) {
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(KEY_NAME, contact.getName()); // Contact Name
        values.put(KEY_PH_NO, contact.getPhoneNumber()); // Contact Phone

        // Inserting Row
        db.insert(TABLE_CONTACTS, null, values);
        db.close(); // Closing database connection
    }

    // Getting single contact
    Contact getContact(int id) {
        SQLiteDatabase db = this.getReadableDatabase();

        Cursor cursor = db.query(TABLE_CONTACTS, new String[] { KEY_ID, KEY_NAME, KEY_PH_NO }, KEY_ID + "=?",
                new String[] { String.valueOf(id) }, null, null, null, null);
        if (cursor != null)
            cursor.moveToFirst();

        Contact contact = new Contact(cursor.getInt(0), cursor.getDouble(1), cursor.getDouble(2));
        // return contact
        return contact;
    }

    // Getting All Contacts
    public List<Contact> getAllContacts() {
        List<Contact> contactList = new ArrayList<Contact>();
        // Select All Query
        String selectQuery = "SELECT  * FROM " + TABLE_CONTACTS;

        SQLiteDatabase db = this.getWritableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);

        // looping through all rows and adding to list
        if (cursor.moveToFirst()) {
            do {
                Contact contact = new Contact();
                contact.setID(cursor.getInt(0));
                contact.setName(cursor.getDouble(1));
                contact.setPhoneNumber(cursor.getDouble(2));
                // Adding contact to list
                contactList.add(contact);
            } while (cursor.moveToNext());
        }

        // return contact list
        return contactList;
    }

    // Updating single contact
    public int updateContact(Contact contact) {
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(KEY_NAME, contact.getName());
        values.put(KEY_PH_NO, contact.getPhoneNumber());

        // updating row
        return db.update(TABLE_CONTACTS, values, KEY_ID + " = ?", new String[] { String.valueOf(contact.getID()) });
    }

    // Deleting single contact
    public void deleteContact(Contact contact) {
        SQLiteDatabase db = this.getWritableDatabase();
        db.delete(TABLE_CONTACTS, KEY_ID + " = ?", new String[] { String.valueOf(contact.getID()) });
        db.close();
    }

    // Getting contacts Count
    public int getContactsCount() {
        String countQuery = "SELECT  * FROM " + TABLE_CONTACTS;
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(countQuery, null);
        cursor.close();

        // return count
        return cursor.getCount();
    }
}

提前致谢。

Answer 1

您没有在Contact对象中设置ID。

db.updateContact(new Contact(consumed, total));

在updateContact方法中：使用以下更新查询：

db.update(TABLE_CONTACTS, values, KEY_ID + " = ?", new String[] { String.valueOf(contact.getID()) });

contact.getID（）返回0，没有id与id 0匹配且没有更新。

你也应该传递正确的身份

Android SQlite更新无法正常工作，没有错误

1 个答案: