Question

如何在数据库中插入另一列，数据/时间戳并在列表视图中显示？我这里有我的数据库专栏：

public class MessagesDBAdapter {

    public static final String KEY_RECIPIENT = "recipient";
    public static final String KEY_MESSAGE = "message";
    public static final String KEY_TIME = "time";
    public static final String KEY_ROWID = "_id";

    private static final String TAG = "MessagesDBAdapter";
    private DatabaseHelper mDbHelper;
    private SQLiteDatabase mDb;

     //Database creation sql statement

    private static final String DATABASE_CREATE =
             "create table notes (" + KEY_ROWID + " integer primary key autoincrement, "
        + KEY_RECIPIENT + " text not null, " + KEY_MESSAGE + " text not null, " + KEY_TIME + " text not null,);";

    private static final String DATABASE_NAME = "data";
    private static final String DATABASE_TABLE = "notes";
    private static final int DATABASE_VERSION = 2;
    public  final String KEY_TIMESTAMP = "timeStamp";


    private final Context mCtx;

    private static class DatabaseHelper extends SQLiteOpenHelper {

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

        @Override
        public void onCreate(SQLiteDatabase db) {
            db.execSQL(DATABASE_CREATE);
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
                    + newVersion + ", which will destroy all old data");
            db.execSQL("DROP TABLE IF EXISTS notes");
            onCreate(db);
        }
    }

    /**
     * Constructor - takes the context to allow the database to be
     * opened/created
     * 
     * @param ctx the Context within which to work
     */
    public MessagesDBAdapter(Context ctx) {
        this.mCtx = ctx;
    }

    public MessagesDBAdapter open() throws SQLException {
        mDbHelper = new DatabaseHelper(mCtx);
        mDb = mDbHelper.getWritableDatabase();
        return this;
    }

    public void close() {
        mDbHelper.close();
    }

    public long createNote(String phoneNo, String message) {
        ContentValues initialValues = new ContentValues();
        initialValues.put(KEY_RECIPIENT, phoneNo);
        initialValues.put(KEY_MESSAGE, message);

        open();

        return mDb.insert(DATABASE_TABLE, null, initialValues);
    }

    public boolean deleteNote(long rowId) {

        return mDb.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0;
    }

    public Cursor fetchAllNotes() {

        return mDb.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_RECIPIENT,
                KEY_MESSAGE}, null, null, null, null, null);
    }

    public Cursor fetchNote(long rowId) throws SQLException {

        Cursor mCursor =

            mDb.query(true, DATABASE_TABLE, new String[] {KEY_ROWID,
                    KEY_RECIPIENT, KEY_MESSAGE}, KEY_ROWID + "=" + rowId, null,
                    null, null, null, null);
        if (mCursor != null) {
            mCursor.moveToFirst();
        }
        return mCursor;

    }

    public boolean updateNote(long rowId, String phoneNo, String message) {
        ContentValues args = new ContentValues();
        args.put(KEY_RECIPIENT, phoneNo);
        args.put(KEY_MESSAGE, message);

        return mDb.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) > 0;
    }
}

我想在我的数据库中插入一个时间戳并将其显示在列表视图中。任何人都可以帮我吗？我是否必须为时间戳插入新列？

此代码中激活了时间戳：

btnSend.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                String phoneNo = editTextRecipient.getText().toString();
                String message = editTextNewMessage.getText().toString(); 
                Log.d(phoneNo, message);
                saveState(phoneNo, message);
                boolean split = false;

                final Toast toast = Toast.makeText(getBaseContext(), 
                         "Your message " + "\"" + message + "\"" + " is sent to " +"\""+ phoneNo+"\"", 
                          Toast.LENGTH_SHORT);

                Runnable showToastRunnable = new Runnable() {
                  public void run() {
                      dialog.cancel();
                      toast.show();
                  }
              };

                if (phoneNo.length()>0 && message.length()>0)  {
                    showProgress();
                    if (count == 0) {
                          handler.postDelayed(showToastRunnable, 0);
                      }
                      else if (count == 1) {
                          handler.postDelayed(showToastRunnable, 15000);
                      }
                      else if (count == 2) {
                          handler.postDelayed(showToastRunnable, 30000);
                      }
                      else if (count == 3) {
                          handler.postDelayed(showToastRunnable, 60000);
                      }
                }

                   // sendSMS(phoneNo, message, split); */
                else
                    Toast.makeText(getBaseContext(), 
                        "Please enter both phone number and message.", 
                        Toast.LENGTH_SHORT).show();
            }
        }); 
mDbHelper.close();
    }

Answer 1

您可以将时间戳列添加为：

CREATE TABLE [myTable]
(
[_id] INTEGER  NOT NULL PRIMARY KEY,
[timestampColumn] TIMESTAMP
);

您可以像以下一样进行审核：

SELECT datetime(timestampColumn, 'localtime') FROM myTable

编辑：

步骤1：为timestamp列声明一个变量

public static final String KEY_TIMESTAMP = "timestampColumn";

第2步：将列添加到表

private static final String DATABASE_CREATE =
             "create table notes (" + KEY_ROWID + " integer primary key autoincrement, "
        + KEY_RECIPIENT + " text not null, " + KEY_MESSAGE + " text not null, " + KEY_TIME + " text not null, "+ KEY_TIMESTAMP +" TIMESTAMP DEFAULT CURRENT_TIMESTAMP );";

步骤3：获取时间戳列以及其他列

public Cursor fetchAllNotes() {

    return mDb.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_RECIPIENT,
            KEY_MESSAGE, KEY_TIMESTAMP}, null, null, null, null, null);
}

步骤4：获取时间戳列以及其他列

public Cursor fetchNote(long rowId) throws SQLException {
    Cursor mCursor =

        mDb.query(true, DATABASE_TABLE, new String[] {KEY_ROWID,
                KEY_RECIPIENT, KEY_MESSAGE, KEY_TIMESTAMP}, KEY_ROWID + "=" + rowId, null,
                null, null, null, null);
    if (mCursor != null) {
        mCursor.moveToFirst();
    }
    return mCursor;

}

您还可以使用rawQuery检索数据，例如：

public Cursor getAllNotes() {

    Cursor mCursor = mDb.rawQuery("SELECT _id, time, message, recipient, datetime(timestampColumn, 'localtime') AS timestampColumn FROM notes", null);
}

Android：数据库中的时间戳

1 个答案: