Question

我有一张结构表：

+---------+--------------+-----------------+---------------+-------+------+
| 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 |
+---------+--------------+-----------------+---------------+-------+------+

当我运行以下声明时：

SELECT * 
FROM   loy_period 
WHERE  To_date('15/04/2015', 'DD/MM/YYYY') BETWEEN 
       To_date(week_start_date, 'DD/MM/YYYY') AND 
       To_date(week_end_date, 'DD/MM/YYYY');

和

SELECT * 
FROM   loy_period 
WHERE  To_date('15/04/2015', 'DD/MM/YYYY') BETWEEN 
       week_start_date AND 
       week_end_date;

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，除了 week_no 51记录外，它还将返回正确的句点！

我很困惑为什么会这样。类型为week_start_date的{{1}}和week_end_date列。

Fiddle按预期工作。

Answer 1

通过正确使用 TO_DATE 和DATE值，它非常适合我。

永远不要在 DATE 上使用 TO_DATE ，它会隐式将其转换为字符串，然后使用特定于语言环境的NLS格式重新定义
'01/01/2015'不是日期，它是一个STRING。您必须使用 TO_DATE 将其明确转换为DATE。

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，应用的实际过滤器是过滤器（TO_DATE（TO_CHAR（SYSDATE @！））由于基于特定于语言环境的NLS格式的隐式转换，您将得到错误的输出。

无论如何，现在回到你原来的问题。

例如，

假设您的数据如下：

<强>设定：

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>

表格

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>

根据DATE范围过滤行的查询：

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>

日期比较返回异常结果 - SQL Oracle

1 个答案: