如何在SQLite Android中删除所有数据历史表的时间早于30天

Question

CREATE TABLE

public static void createTable(SQLiteDatabase db){  
String sql = "CREATE TABLE " + TABLE_HISTORY + " ("  
                    + COL_ID + " INTEGER PRIMARY KEY NOT NULL, "  
                    + COL_TITLE + " TEXT, "  
                    + COL_MEDIA_NAME + " TEXT, "  
                    + COL_IMAGE_URL + " TEXT, "  
                    + COL_URL + " TEXT, "  
                    + COL_CREATED_AT + " INTEGER NOT NULL DEFAULT 0, "  
                    + COL_UPDATED_AT + " INTEGER NOT NULL DEFAULT 0 "  
                    + ")";  
    db.execSQL(sql);  
}

INSERT TABLE

 public static long insertTableHistory(DatabaseDAO db, int mId, String title, String mediaName, String imageUrl, String url) {
    SQLiteDatabase database = db.getWritableDatabase();
    String sql =
            "INSERT INTO " + TABLE_HISTORY + " ("
                    + COL_ID + ", "
                    + COL_TITLE + ", "
                    + COL_MEDIA_NAME + ", "
                    + COL_IMAGE_URL + ", "
                    + COL_URL + ", "
                    + COL_CREATED_AT + ","
                    + COL_UPDATED_AT +
                    ")"
                    + " VALUES (?, ?, ?, ?, ?, ?, ?, ?)";
SQLiteStatement statement = database.compileStatement(sql);
    long id = -1;
    try {
        database.beginTransaction();
        statement.clearBindings();
        statement.bindLong(1, mId);
        statement.bindString(2, title);
        statement.bindString(3, mediaName);
        statement.bindString(4, imageUrl);
        statement.bindString(5, url);
        statement.bindLong(6, System.currentTimeMillis());
        statement.bindLong(7, System.currentTimeMillis());
        id = statement.executeInsert();
        database.setTransactionSuccessful();

    } catch (Exception e) {
        database.endTransaction();
    } finally {
        database.endTransaction();
    }
    return id;
}

I try it But it not working.

public static void deleteDataOlderThan30Days(DatabaseDAO databaseDAO) {

    String sql = "DELETE FROM " + TABLE_HISTORY + " WHERE " + COL_CREATED_AT + "<= date('now','-30 day')";
    SQLiteDatabase database = databaseDAO.getWritableDatabase();
    database.execSQL(sql);
}

How to I can delete all data at HistotyTable older than 30days?
Please. Help me!

Answer 1

Your timestamp columns contain a number, which is the number of milliseconds since 1970. The date function returns a string in the format yyyy-mm-dd .

Either change your database to store the timestamps in the same format, or change the query to compute the date limit in the millisecond format:

... WHERE CreatedAt <= strftime('%s', 'now', '-30 days') * 1000

Answer 2

Used datediff function

When it comes to SQL, you have to specify what you mean by "older than a day".

DATEDIFF: it uses day boundary midnight so run it at 19th October 00:05 and you'll delete rows 6 minutes old (18th October 23:59)

24 hours?

Yesterday midnight? Run code on 19th October, delete rows before 18th?

Also, don't put a function on a column.

This assumes 24 hours to the minute:

DELETE MyTableWhere WHERE MyColumn < DATEADD(day, -1, GETDATE()) This assumes yesterday midnight:

DELETE MyTableWhere WHERE MyColumn < DATEADD(DAY, DATEDIFF(DAY, 0, GETDATE()), -1)