Question

我有2个值，imsi和电话号码。我将它们存储在database.i中获取getSIMContacts中的数据库问题functn.addContact将phonenum添加到数据库中。 getSIMContacts从数据库中检索phonenum。我的代码看起来像这样 - ＆gt;

public class PersonalContactsDatabase extends SQLiteOpenHelper {

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

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

    // Contacts table name
    private static final String TABLE_NAME = "Contacts";

    // Contacts Table Columns names
    private static final String KEY_ID = "id";
    private static final String IMEI_MOB = "imei";
    private static final String KEY_MO_NO = "mobile_no";

    Contact contact;

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


    // Creating Tables
   @Override
    public void onCreate(SQLiteDatabase db) {
        String CREATE_CONTACTS_TABLE = "CREATE TABLE " + TABLE_NAME + "("
                + KEY_ID + " TEXT PRIMARY KEY," 
                + KEY_MO_NO + " TEXT,"
                + IMEI_MOB + " TEXT" 
                + ")";

        System.out.println("Create Query :::::"+CREATE_CONTACTS_TABLE);
        db.execSQL(CREATE_CONTACTS_TABLE);

        Log.e("DB Manager", "Db created Succesfully "+db);
        //Toast.makeText(context, text, duration)
    }

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

        // Create tables again
        onCreate(db);
    }

    /**
     * All CRUD(Create, Read, Update, Delete) Operations
     */

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

        ContentValues values = new ContentValues();
        //values.put(IMEI_MOB, contact.getImei()); // Contact Name
        values.put(KEY_MO_NO, contact); // Contact Phone

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

    public List<String> getSIMContacts() {
        List<String> contactList = new ArrayList<String>();
        // Select All Query
        String selectQuery = "SELECT " + KEY_MO_NO +" FROM " + TABLE_NAME;

        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.setStrId(Integer.parseInt(cursor.getString(0)));
                //contact.setName(cursor.getString(1));
                contact.setMobileNum(cursor.getString(2));*/
                // Adding contact to list
                contactList.add(cursor.getString(0));
            } while (cursor.moveToNext());
        }
        cursor.close();
        // return contact list
        return contactList;
    }

读取帖子并编辑数据。我做了更改但是当我检索数据时，我进入无限循环。代码如下

saveButton.setOnClickListener(new OnClickListener() {
              @Override
              public void onClick(View v) {
                  List<String> list;
                  list=db.getSIMContacts();
                  while(list.iterator().hasNext())
                  {
                      String retrieved_num=list.iterator().next();
                      listItems.add(retrieved_num); 
                      adapter.notifyDataSetChanged();

                  }

              }
      });

在这个数据库中，我希望KEY_ID是主键，具有自动递增和递减功能，并且还有另一个函数用于获取与键id值对应的移动数字。它看起来像这样但有一些问题。请帮我解决一下

String getContact(int id) {
    String str="";
        try{
        SQLiteDatabase db = this.getReadableDatabase();

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

         str+=cursor.getString(2);
        // return contact
        cursor.close();
        }catch(Exception e)
        {
            Log.e("Get Contact Exception", ""+e);
        }
        return str;
    }

Answer 1

您的查询错误，因为您在引号中指定了字段KEY_MO_NO。

此

  String selectQuery = "SELECT " + "KEY_MO_NO" +" FROM " + TABLE_NAME;

应该是

 String selectQuery = "SELECT " + KEY_MO_NO +" FROM " + TABLE_NAME;

从数据库中检索rawquery android无法正常工作

1 个答案: