Android SQLitedatabase [duplicate]

This question already has an answer here:

• What is The use of moveToFirst () in SQLite Cursors 4 answers

Why do we have to move to the first item in the code below? I thought the cursor would only contain one row since the rowId is a primary key

    // Fetch single reminder
@SuppressLint("NewApi")
public Cursor fetchReminder(long rowId) throws SQLException {
    Cursor myCursor = db.query(true, DATABASE_TABLE, new String[] {
            KEY_ROW_ID, KEY_TITLE, KEY_BODY, KEY_DATE_TIME }, KEY_ROW_ID
            + "=" + rowId, null, null, null, null, null, null);
    if (myCursor != null) {
        myCursor.moveToFirst();
    }
    return myCursor;
}