Question

这是我日期的数据库结构：

如果今天是2017/9/22，我想得到3个2017/9/24 2017/9/25 2017/9/29的结果。

在我的DatabaseHandler类中，我尝试了以下代码：

public List<Contact> latestDays() {
        List<Contact> contactList = new ArrayList<>();
        // My database time format is: yyyymdd
        Calendar mCalendar = new GregorianCalendar();
        int mYear = mCalendar.get(Calendar.YEAR);
        int mMonth = mCalendar.get(Calendar.MONTH)+1;
        int mDay = mCalendar.get(Calendar.DAY_OF_MONTH);
        String today = String.valueOf(mYear).concat(String.valueOf(mMonth).concat(String.valueOf(mDay)));
        System.out.println(today+"today");
        SQLiteDatabase db = this.getWritableDatabase();

        String selectQuery = "SELECT * FROM " + TABLE_CONTACTS + " WHERE date > (SELECT DATETIME('" + today + "'," + "'-7" + " day'))";
        Cursor cursor = db.rawQuery(selectQuery, null);
//looping through all rows and adding to list
        if (cursor.moveToFirst()) {
            do {
                Contact contact = new Contact();
                contact.setID(Integer.parseInt(cursor.getString(0)));
                contact.setDate(cursor.getString(1));
                contact.setBeforeMorning(cursor.getString(2));
                contact.setAfterMorning(cursor.getString(3));
                contact.setBeforeNoon(cursor.getString(4));
                contact.setAfterNoon(cursor.getString(5));
                contact.setBeforeNight(cursor.getString(6));
                contact.setAfterNight(cursor.getString(7));
                System.out.println("The result is :" + cursor.getString(1));
                //Adding contact to list
                contactList.add(contact);
            } while (cursor.moveToNext());
        }

        return contactList;
    }

我在我的MainActivity上这样称呼它：

private DatabaseHandler db;
contactList = db.latestDays();
System.out.println(contactList.size());

我打印结果如下：

我得到了所有记录，但这不是我想要的。

原因可能是我的日期格式，所以我将yyyymmdd的所有日期排序添加到raqQuery：

Cursor cursor = db.rawQuery("SELECT * FROM " + TABLE_CONTACTS +" WHERE date > (SELECT DATETIME('" + today + "'," + "'-7" + " day'))" +
                " ORDER BY\n" +
                " SUBSTR(Date, 1, 4) DESC,\n" +
                " CASE WHEN INSTR(SUBSTR(Date, 6), '/') = 2\n" +
                " THEN '0' || SUBSTR(Date, 6, 1)\n" +
                " ELSE SUBSTR(Date, 6, 2) END DESC,\n" +
                " CASE WHEN LENGTH(SUBSTR(SUBSTR(Date, 6), INSTR(SUBSTR(Date, 6), '/') + 1)) = 1\n" +
                " THEN '0' || SUBSTR(SUBSTR(Date, 6), INSTR(SUBSTR(Date, 6), '/') + 1)\n" +
                " ELSE SUBSTR(SUBSTR(Date, 6), INSTR(SUBSTR(Date, 6), '/') + 1) END DESC; ",null);

我仍然得到相同的结果......

所以我试图找到另一个解决方案并尝试这样，我改变了SQL搜索语法：

        Calendar mCalendar = new GregorianCalendar();
        int mYear = mCalendar.get(Calendar.YEAR);
        int mMonth = mCalendar.get(Calendar.MONTH)+1;
        int mDay = mCalendar.get(Calendar.DAY_OF_MONTH);
        String today = String.valueOf(mYear).concat(String.valueOf(mMonth).concat(String.valueOf(mDay)));
        System.out.println(today+"today");
        Calendar theEnd = Calendar.getInstance();
        Calendar theStart = (Calendar) theEnd.clone();

        theStart.add(Calendar.DAY_OF_MONTH, -7);

        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-M-dd");
        String start = dateFormat.format(theStart.getTime());
        String end = dateFormat.format(theEnd.getTime());

        // Now you have date boundaries in TEXT format

        Cursor cursor = db.rawQuery("SELECT * FROM contacts WHERE date BETWEEN "+start+" AND "+end +
                        " ORDER BY\n" +
                        " SUBSTR(Date, 1, 4) DESC,\n" +
                        " CASE WHEN INSTR(SUBSTR(Date, 6), '/') = 2\n" +
                        " THEN '0' || SUBSTR(Date, 6, 1)\n" +
                        " ELSE SUBSTR(Date, 6, 2) END DESC,\n" +
                        " CASE WHEN LENGTH(SUBSTR(SUBSTR(Date, 6), INSTR(SUBSTR(Date, 6), '/') + 1)) = 1\n" +
                        " THEN '0' || SUBSTR(SUBSTR(Date, 6), INSTR(SUBSTR(Date, 6), '/') + 1)\n" +
                        " ELSE SUBSTR(SUBSTR(Date, 6), INSTR(SUBSTR(Date, 6), '/') + 1) END DESC; ", null);

更糟糕的是，我没有得到任何数据。

如果我的数据库时间格式是yyyymdd，我到底能获得最近7天的时间吗？

Answer 1

试试这个

final LocalDate currentDate= LocalDate.now();
final LocalDate date7Days = date.minusDays(7);
//Format and display date
final String formattedDate = date7Days.format(DateTimeFormatter.ISO_LOCAL_DATE);
System.out.println(formattedDate);

根据您的日期时间格式进行更改

如何获取日期格式为yyyymdd的最近7天

1 个答案: