代码如下：

select  days,

max(decode(flag2, 1, days, null)) over(partition by flag1) new_sunday

from

(select days,

to_char(days, 'iw') flag1,

to_char(days, 'D') flag2,

max(decode(days, to_date(&var_days, 'yyyy/mm/dd'), to_char(days, 'iw'), null)) over() flag3

from t)

where flag1 = flag3

测试如下：

SQL> select * from t;

DAYS

-----------

2016/8/1

2016/8/2

2016/8/3

2016/8/4

2016/8/5

2016/8/6

2016/8/7

2016/10/1

2016/10/2

2016/10/3

2016/10/4

2016/10/5

2016/10/6

2016/10/7

2016/10/8

2016/10/9

2016/10/10

2016/10/11

2016/10/12

2016/10/13

DAYS

-----------

2016/10/14

2016/10/15

2016/10/16

2016/10/17

2016/10/18

2016/10/19

2016/10/20

2016/10/21

2016/10/22

2016/10/23

2016/10/24

2016/10/25

2016/10/26

2016/10/27

2016/10/28

2016/10/29

2016/10/30

2016/10/31

38 rows selected

--test 1

SQL> select  days,

2          max(decode(flag2, 1, days, null)) over(partition by flag1) new_sunday

3  from

4  (select days,

5          to_char(days, 'iw') flag1,

6          to_char(days, 'D') flag2,

7          max(decode(days, to_date('2016/8/1', 'yyyy/mm/dd'), to_char(days, 'iw'), null)) over() flag3

8     from t)

9  where flag1 = flag3

10  /

DAYS        NEW_SUNDAY

----------- -----------

2016/8/1    2016/8/7

2016/8/2    2016/8/7

2016/8/3    2016/8/7

2016/8/7    2016/8/7

2016/8/5    2016/8/7

2016/8/6    2016/8/7

2016/8/4    2016/8/7

--test 2

SQL> select  days,

2          max(decode(flag2, 1, days, null)) over(partition by flag1) new_sunday

3  from

4  (select days,

5          to_char(days, 'iw') flag1,

6          to_char(days, 'D') flag2,

7          max(decode(days, to_date('2016/10/17', 'yyyy/mm/dd'), to_char(days, 'iw'), null)) over() flag3

8     from t)

9  where flag1 = flag3

10  /

DAYS        NEW_SUNDAY

----------- -----------

2016/10/17  2016/10/23

2016/10/18  2016/10/23

2016/10/19  2016/10/23

2016/10/23  2016/10/23

2016/10/21  2016/10/23

2016/10/22  2016/10/23

2016/10/20  2016/10/23

7 rows selected