Sorting dates in sqlite database?

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清酒与你
清酒与你 2020-12-10 07:55

I have developed an App ..For that I have a database and it has many tables. One of the table has date column. My question is I have to sort the dates and have to pick olde

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  • 2020-12-10 08:31

    You can change how it is being stored. Instead of one column, have 3:
    month , day , year ;


    This allows more flexibilityand you can sort it more easily. Since it is numbers month(1-12) instead of strings, it will be more easily sorted.

    SELECT month,day,year
    FROM tables
    ORDER BY month,day,year DESC;
    
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  • 2020-12-10 08:38

    Firstly, you cannot store the type "date" in sqlite. I'm sure that there are plenty of equally laudable ways of achieving this but here's how i personally do what you're asking. I convert all my dates to this string format: new SimpleDateFormat("yyyyMMdd"); I put that into my database. It's convenient and i hope for self-evident reasons. And when i want to return my dates, i simply use an order in the query like "date DESC". then i reconvert it to whatever format i needed them in.

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  • 2020-12-10 08:48

    In sqlite does not really have a date type. You can store dates as strings using one of their predefined formats see http://www.sqlite.org/lang_datefunc.html for more information.

    A time string can be in any of the following formats:

    YYYY-MM-DD
    YYYY-MM-DD HH:MM
    YYYY-MM-DD HH:MM:SS
    YYYY-MM-DD HH:MM:SS.SSS
    YYYY-MM-DDTHH:MM
    YYYY-MM-DDTHH:MM:SS
    YYYY-MM-DDTHH:MM:SS.SSS
    HH:MM
    HH:MM:SS
    HH:MM:SS.SSS
    now
    DDDDDDDDDD
    

    You need to store them in YYYY-MM-DD then you can sort them order by asc limit 1 to get the oldest date. So instead of

    Column_Date
    ------------
    Nov-07-2012
    Nov-21-2012
    Nov-25-2012
    Oct-25-2012
    Oct-24-2102
    

    You will have to store them like this instead

    Column_Date
    ------------
    2012-11-07
    2012-11-21
    2012-11-25
    2012-10-25
    2012-10-24
    

    Finally you read the rows if any

    Cursor oldestDateCursor = db.query("DateTableName", null, null, null, null, null, "date_column ASC LIMIT 1");
    if (oldestDateCursor.moveToFirst())
    {
        String date = oldestDateCursor.getColumnName(oldestDateCursor.getColumnIndex("date_column"));
    }
    oldestDateCursor.close();
    
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