日期比较返回异常结果-SQL Oracle

我有一个结构表：

+---------+--------------+-----------------+---------------+-------+------+ | week_no | long_week_no | week_start_date | week_end_date | month | year | +---------+--------------+-----------------+---------------+-------+------+ | 1 | 1A | 01/01/2015 | 03/01/2015 | JAN | 2015 | | 1 | 1B | 04/01/2015 | 10/01/2015 | JAN | 2015 | | 2 | 2 | 11/01/2015 | 17/01/2015 | JAN | 2015 | | 3 | 3 | 18/01/2015 | 24/01/2015 | JAN | 2015 | | .. | .. | .. | .. | .. | .. | | 51 | 51 | 14/12/2014 | 20/12/2015 | DEC | 2014 | +---------+--------------+-----------------+---------------+-------+------+ 及

它返回以下内容：

+---------+--------------+-----------------+---------------+-------+------+ | week_no | long_week_no | week_start_date | week_end_date | month | year | +---------+--------------+-----------------+---------------+-------+------+ | 51 | 51 | 14/12/2014 | 20/12/2015 | DEC | 2014 | | 1 | 1A | 01/01/2015 | 03/01/2015 | JAN | 2015 | +---------+--------------+-----------------+---------------+-------+------+ 当我以任何日期运行它时，它将返回除第51周记录之外的正确周期

我不明白为什么会这样。日期类型的“开始日期”和“结束日期”两列

---

正常工作。

正确使用“截止日期”和“日期”值对我来说非常有效

不要在日期上使用TO_DATE，它会隐式地将其转换为字符串，然后使用特定于语言环境的NLS格式返回到日期

“01/01/2015”不是日期，而是字符串。必须使用TO_DATE将其显式转换为日期

看看会发生什么：

SQL> explain plan for select * from dual where to_date(sysdate) > to_date(sysdate -1);

Explained.

SQL> select * from table(dbms_xplan.display);

PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
Plan hash value: 3752461848

---------------------------------------------------------------------------
| Id  | Operation          | Name | Rows  | Bytes | Cost (%CPU)| Time     |
---------------------------------------------------------------------------
|   0 | SELECT STATEMENT   |      |     1 |     2 |     2   (0)| 00:00:01 |
|*  1 |  FILTER            |      |       |       |            |          |
|   2 |   TABLE ACCESS FULL| DUAL |     1 |     2 |     2   (0)| 00:00:01 |
---------------------------------------------------------------------------

Predicate Information (identified by operation id):

PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
---------------------------------------------------

   1 - filter(TO_DATE(TO_CHAR(SYSDATE@!))>TO_DATE(TO_CHAR(SYSDATE@!-1)))

14 rows selected.

SQL>

因此，实际应用的过滤器是filterTO_DATETO_CHARSYSDATE@！由于基于特定于语言环境的NLS格式的隐式转换，您将获得不正确的输出

无论如何，现在回到你原来的问题

比如说,

假设您的数据如下所示：

设置：

表:

根据日期范围筛选行的查询：

---

如果他们已经是date类型的，你到底为什么要在他们身上打电话叫date？千万不要在date列上用To-date。它会隐式地将其转换为字符串，然后使用特定于语言环境的NLS格式返回到最新状态。您能将示例数据和查询的合理版本放入其中吗？您确定第51行中的年份正确吗？您需要处理该小提琴，直到它显示出您请求帮助的问题，或者您自己发现问题为止。 +---------+--------------+-----------------+---------------+-------+------+ | week_no | long_week_no | week_start_date | week_end_date | month | year | +---------+--------------+-----------------+---------------+-------+------+ | 51 | 51 | 14/12/2014 | 20/12/2015 | DEC | 2014 | | 1 | 1A | 01/01/2015 | 03/01/2015 | JAN | 2015 | +---------+--------------+-----------------+---------------+-------+------+

SQL> explain plan for select * from dual where to_date(sysdate) > to_date(sysdate -1);

Explained.

SQL> select * from table(dbms_xplan.display);

PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
Plan hash value: 3752461848

---------------------------------------------------------------------------
| Id  | Operation          | Name | Rows  | Bytes | Cost (%CPU)| Time     |
---------------------------------------------------------------------------
|   0 | SELECT STATEMENT   |      |     1 |     2 |     2   (0)| 00:00:01 |
|*  1 |  FILTER            |      |       |       |            |          |
|   2 |   TABLE ACCESS FULL| DUAL |     1 |     2 |     2   (0)| 00:00:01 |
---------------------------------------------------------------------------

Predicate Information (identified by operation id):

PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
---------------------------------------------------

   1 - filter(TO_DATE(TO_CHAR(SYSDATE@!))>TO_DATE(TO_CHAR(SYSDATE@!-1)))

14 rows selected.

SQL>

SQL> CREATE TABLE t
  2      (week_no VARCHAR2(2), long_week_no VARCHAR2(2), week_start_date DATE, week_end_date DATE, mnth VARCHAR2(3), yr VARCHAR2(4))
  3  ;

Table created.

SQL>
SQL>
SQL> INSERT ALL
  2      INTO t (week_no, long_week_no, week_start_date, week_end_date, mnth, yr)
  3           VALUES ('1', '1A', TO_DATE('01/01/2015','DD/MM/YYYY'), TO_DATE('03/01/2015','DD/MM/YYYY'), 'JAN', '2015')
  4      INTO t (week_no, long_week_no, week_start_date, week_end_date, mnth, yr)
  5           VALUES ('1', '1B', TO_DATE('04/01/2015','DD/MM/YYYY'), TO_DATE('10/01/2015','DD/MM/YYYY'), 'JAN', '2015')
  6      INTO t (week_no, long_week_no, week_start_date, week_end_date, mnth, yr)
  7           VALUES ('2', '2', TO_DATE('11/01/2015','DD/MM/YYYY'), TO_DATE('17/01/2015','DD/MM/YYYY'), 'JAN', '2015')
  8      INTO t (week_no, long_week_no, week_start_date, week_end_date, mnth, yr)
  9           VALUES ('3', '3', TO_DATE('18/01/2015','DD/MM/YYYY'), TO_DATE('24/01/2015','DD/MM/YYYY'), 'JAN', '2015')
 10      INTO t (week_no, long_week_no, week_start_date, week_end_date, mnth, yr)
 11           VALUES ('51', '51', TO_DATE('20/12/2014','DD/MM/YYYY'), TO_DATE('26/12/2015','DD/MM/YYYY'), 'DEC', '2014')
 12  SELECT * FROM dual
 13  ;

5 rows created.

SQL>
SQL> COMMIT;

Commit complete.

SQL>

SQL> SELECT * FROM t;

WE LO WEEK_STAR WEEK_END_ MNT YR
-- -- --------- --------- --- ----
1  1A 01-JAN-15 03-JAN-15 JAN 2015
1  1B 04-JAN-15 10-JAN-15 JAN 2015
2  2  11-JAN-15 17-JAN-15 JAN 2015
3  3  18-JAN-15 24-JAN-15 JAN 2015
51 51 20-DEC-14 26-DEC-15 DEC 2014

SQL>

SQL> SELECT *
  2  FROM   t
  3  WHERE  To_date('15/01/2015', 'DD/MM/YYYY') BETWEEN
  4         week_start_date AND
  5         week_end_date;

WE LO WEEK_STAR WEEK_END_ MNT YR
-- -- --------- --------- --- ----
2  2  11-JAN-15 17-JAN-15 JAN 2015
51 51 20-DEC-14 26-DEC-15 DEC 2014

SQL>