我在使用SQLite的Android应用程序上处理日期遇到了一些麻烦。 我有几个问题:

我应该使用什么类型存储日期在SQLite(文本,整数,…)? 给出了存储日期的最佳方式,我如何使用ContentValues正确存储它? 从SQLite数据库中检索日期的最佳方法是什么? 如何在SQLite上进行sql选择,按日期排序结果?


当前回答

As presumed in this comment, I'd always use integers to store dates. For storing, you could use a utility method public static Long persistDate(Date date) { if (date != null) { return date.getTime(); } return null; } like so: ContentValues values = new ContentValues(); values.put(COLUMN_NAME, persistDate(entity.getDate())); long id = db.insertOrThrow(TABLE_NAME, null, values); Another utility method takes care of the loading public static Date loadDate(Cursor cursor, int index) { if (cursor.isNull(index)) { return null; } return new Date(cursor.getLong(index)); } can be used like this: entity.setDate(loadDate(cursor, INDEX)); Ordering by date is simple SQL ORDER clause (because we have a numeric column). The following will order descending (that is newest date goes first): public static final String QUERY = "SELECT table._id, table.dateCol FROM table ORDER BY table.dateCol DESC"; //... Cursor cursor = rawQuery(QUERY, null); cursor.moveToFirst(); while (!cursor.isAfterLast()) { // Process results }

始终确保存储UTC/GMT时间,特别是在使用java.util.Calendar和java.text.SimpleDateFormat使用默认(即您的设备的)时区时。 使用java.util.Date.Date()是安全的,因为它创建了一个UTC值。

其他回答

通常(与我在mysql/postgres中所做的一样),我将日期存储在int(mysql/post)或文本(sqlite)中,以时间戳格式存储它们。

然后,我将它们转换为日期对象,并根据用户时区执行操作

"SELECT  "+_ID+" ,  "+_DESCRIPTION +","+_CREATED_DATE +","+_DATE_TIME+" FROM "+TBL_NOTIFICATION+" ORDER BY "+"strftime(%s,"+_DATE_TIME+") DESC";

1 -就像StErMi说的。

2 -请阅读:http://www.vogella.de/articles/AndroidSQLite/article.html

3 -

Cursor cursor = db.query(TABLE_NAME, new String[] {"_id", "title", "title_raw", "timestamp"}, 
                "//** YOUR REQUEST**//", null, null, "timestamp", null);

在这里看到的:

查询()在SQLiteDatabase

4 -见答案3

在SQlite DB中存储日期的最佳方法是存储当前的datetimemillisseconds。下面是执行so_的代码片段

获取datetimemillisseconds

public static long getTimeMillis(String dateString, String dateFormat) throws ParseException {
    /*Use date format as according to your need! Ex. - yyyy/MM/dd HH:mm:ss */
    String myDate = dateString;//"2017/12/20 18:10:45";
    SimpleDateFormat sdf = new SimpleDateFormat(dateFormat/*"yyyy/MM/dd HH:mm:ss"*/);
    Date date = sdf.parse(myDate);
    long millis = date.getTime();

    return millis;
}

在数据库中插入数据

public void insert(Context mContext, long dateTimeMillis, String msg) {
    //Your DB Helper
    MyDatabaseHelper dbHelper = new MyDatabaseHelper(mContext);
    database = dbHelper.getWritableDatabase();

    ContentValues contentValue = new ContentValues();
    contentValue.put(MyDatabaseHelper.DATE_MILLIS, dateTimeMillis);
    contentValue.put(MyDatabaseHelper.MESSAGE, msg);

    //insert data in DB
    database.insert("your_table_name", null, contentValue);

   //Close the DB connection.
   dbHelper.close(); 

}

现在,您的数据(日期在currenttimemillisecseconds中)被插入到DB中。

下一步是,当您想从DB检索数据时,您需要将各自的日期时间毫秒转换为相应的日期。下面是执行相同操作的示例代码片段_

将日期毫秒转换为日期字符串。

public static String getDate(long milliSeconds, String dateFormat)
{
    // Create a DateFormatter object for displaying date in specified format.
    SimpleDateFormat formatter = new SimpleDateFormat(dateFormat/*"yyyy/MM/dd HH:mm:ss"*/);

    // Create a calendar object that will convert the date and time value in milliseconds to date.
    Calendar calendar = Calendar.getInstance();
    calendar.setTimeInMillis(milliSeconds);
    return formatter.format(calendar.getTime());
}

现在,最后获取数据,看看它的工作…

public ArrayList<String> fetchData() {

    ArrayList<String> listOfAllDates = new ArrayList<String>();
    String cDate = null;

    MyDatabaseHelper dbHelper = new MyDatabaseHelper("your_app_context");
    database = dbHelper.getWritableDatabase();

    String[] columns = new String[] {MyDatabaseHelper.DATE_MILLIS, MyDatabaseHelper.MESSAGE};
    Cursor cursor = database.query("your_table_name", columns, null, null, null, null, null);

    if (cursor != null) {

        if (cursor.moveToFirst()){
            do{
                //iterate the cursor to get data.
                cDate = getDate(cursor.getLong(cursor.getColumnIndex(MyDatabaseHelper.DATE_MILLIS)), "yyyy/MM/dd HH:mm:ss");

                listOfAllDates.add(cDate);

            }while(cursor.moveToNext());
        }
        cursor.close();

    //Close the DB connection.
    dbHelper.close(); 

    return listOfAllDates;

}

希望这对大家有所帮助!:)

我更喜欢这个。这不是最好的方法,但却是一个快速的解决方案。

//Building the table includes:
StringBuilder query= new StringBuilder();
query.append("CREATE TABLE "+TABLE_NAME+ " (");
query.append(COLUMN_ID+"int primary key autoincrement,");
query.append(COLUMN_CREATION_DATE+" DATE)");

//Inserting the data includes this:
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
values.put(COLUMN_CREATION_DATE,dateFormat.format(reactionGame.getCreationDate())); 

// Fetching the data includes this:
try {
   java.util.Date creationDate = dateFormat.parse(cursor.getString(0);
   YourObject.setCreationDate(creationDate));
} catch (Exception e) {
   YourObject.setCreationDate(null);
}