Perbandingan tanggal mengembalikan hasil yang tidak biasa - SQL Oracle

Ini bekerja sempurna untuk saya dengan proper penggunaan TO_DATE dan nilai DATE.

• Jangan pernah menggunakan TO_DATE pada TANGGAL , Ini akan secara implisit mengubahnya menjadi string dan kemudian kembali ke tanggal menggunakan format NLS khusus lokal .

• '01/01/2015' BUKAN TANGGAL, ini STRING. Anda harus menggunakan TO_DATE untuk secara eksplisit mengubahnya menjadi DATE.

Lihat apa yang terjadi:

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([email protected]!))>TO_DATE(TO_CHAR([email protected]!-1)))

14 rows selected.

SQL>

Jadi, filter sebenarnya yang diterapkan adalah filter(TO_DATE(TO_CHAR([email protected] !)) Anda akan mendapatkan hasil yang salah karena konversi implisit berdasarkan format NLS khusus lokal.

Bagaimanapun, sekarang kembali ke pertanyaan awal Anda.

Misalnya,

Katakanlah data Anda terlihat seperti:

Penyiapan:

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>

Tabel:

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>

Kueri untuk memfilter baris berdasarkan rentang DATE:

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>