Android Sqlite數據庫查詢或刪除N天前數據

最近這幾天項目需要好久不寫SQL語句了都有寫忘了,新需求是定時刪除數據,以防數據太多.

剛開始寫的時候也是各種碰釘子,遇到了各種問題,也在網上找了一些操作語句,但是有些在SQLite裏面不能用,然後開始自己想啊

這些是在網上找的,基本全是刪除用的

//                String a="DELETE FROM Student WHERE time('now', '-7 day') >= date(CreatedTime)";
//                String b="DELETE FROM Student WHERE time('now', '-2 hours') >= date(CreatedTime)";
//                String c="delete from Student where (TO_DAYS(NOW()) - TO_DAYS(time))>=7";
//                String d="delete from Student WHERE TO_DAYS(NOW()) - TO_DAYS(time) <= 7";
//                String f="DELETE FROM Student WHERE EVENT_TIME IS NULL OR DATE(EVENT_TIME) <= DATE(DATE_SUB(NOW(),INTERVAL 7 DAY))";
//                String e="DELETE FROM Student where DATE_SUB(CURDATE(), INTERVAL 7 DAY) <= date(time);";
//                String g="DELETE FROM Student where TO_DAYS(NOW())-TO_DAYS(time)>1;";
//                String h="DELETE FROM Student WHERE date('now', '-7 day') >= date(time);";
//                String i="DELETE FROM Student WHERE julianday('now') - julianday(time) >= 7;";

可能在別的數據庫裏面可以用到吧

廢話也不多說了直接上代碼了

查詢語句:

select * from 表名where 字段名>='2017-06-01' and 字段<='2017-06-05';

刪除語句:

DELETE FROM 表名 WHERE 時間的字段名 <'2019-04-11 14:45:00';

爲什麼最後面的時間那樣寫呢,因爲我時間格式化爲 yyyy-MM-dd HH:mm:ss這樣的

刪除N天前的

DELETE FROM 表名  WHERE   時間的字段名 <' "+getOldDate(N)+" ';

getOldDate這個方法是獲取N天前的日期

 public static String getOldDate(int distanceDay) {
        SimpleDateFormat dft = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        Date beginDate = new Date();
        Calendar date = Calendar.getInstance();
        date.setTime(beginDate);
        date.set(Calendar.DATE, date.get(Calendar.DATE) - distanceDay);    //加號爲N天前
//        date.set(Calendar.DATE, date.get(Calendar.DATE) + distanceDay); //加號爲N天后
        Date endDate = null;
        try {
            endDate = dft.parse(dft.format(date.getTime()));
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return dft.format(endDate);
    }

最後還是問了以爲大佬,他給了我靈感,然後寫出來了當時的心情啊

甚至還有點想

如果這些東西對大家有用處點個讚唄