Arrondir une date

On est souvent confronté à la problématique suivante, comment arrondir une date en dehors des sentiers tracés par trunc (la minute, l’heure, la semaine …) et donc stackoverflow donne ces exemples de réponses pour arrondir une date à 10 minutes mais qui sont facilement extrapolables à d’autres intervals :

Le plus compréhensible

SELECT
  sysdate, TRUNC(sysdate, 'MI') - MOD(TO_CHAR(sysdate, 'MI'), 10) / (24 * 60)
FROM dual;

Le moins lisible

select
  trunc(sysdate, 'mi') - numtodsinterval(mod(EXTRACT(minute FROM cast(sysdate as timestamp)), 10), 'minute')
from dual;

Le plus à jour

select
  trunc(sysdate, 'mi') 
  - mod(EXTRACT(minute FROM cast(sysdate as timestamp)), 10) / (24 * 60)
from dual;

Au niveau du coût pour les 3 on a (avec un temps d’execution identique inférieur au centième de seconde) :

-----------------------------------------------------------------
| Id  | Operation        | Name | Rows  | Cost (%CPU)| Time     |
-----------------------------------------------------------------
|   0 | SELECT STATEMENT |      |     1 |     2   (0)| 00:00:01 |
|   1 |  FAST DUAL       |      |     1 |     2   (0)| 00:00:01 |
-----------------------------------------------------------------


Statistics
----------------------------------------------------------
          1  recursive calls
          0  db block gets
          0  consistent gets
          0  physical reads
          0  redo size
        657  bytes sent via SQL*Net to client
        520  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          1  rows processed

Un exemple ?

alter session set NLS_DATE_FORMAT='YY-MM-DDHH24:MI:SS' ;

col DT   for a8 wrap
col S10  for a8 wrap
col M    for a8 wrap
col M5   for a8 wrap
col M10  for a8 wrap
col M15  for a8 wrap
col M30  for a8 wrap
col H2   for a8 wrap
col H3   for a8 wrap
col H6   for a8 wrap
col H8   for a8 wrap
col H12  for a8 wrap
col DAY  for a8 wrap
col WEEK for a8 wrap

select sysdate                                                                                     DT
     , sysdate - mod(EXTRACT(second FROM cast(sysdate as timestamp)), 10) / (24 * 60 * 60)         S10
     , trunc(sysdate, 'mi')                                                                        M
     , trunc(sysdate, 'mi') - mod(EXTRACT(minute FROM cast(sysdate as timestamp)), 5) / (24 * 60)  M5
     , trunc(sysdate, 'mi') - mod(EXTRACT(minute FROM cast(sysdate as timestamp)), 10) / (24 * 60) M10
     , trunc(sysdate, 'mi') - mod(EXTRACT(minute FROM cast(sysdate as timestamp)), 15) / (24 * 60) M15
     , trunc(sysdate, 'mi') - mod(EXTRACT(minute FROM cast(sysdate as timestamp)), 30) / (24 * 60) M30
     , trunc(sysdate, 'hh24') - mod(EXTRACT(hour FROM cast(sysdate as timestamp)), 2) / 24         H2
     , trunc(sysdate, 'hh24') - mod(EXTRACT(hour FROM cast(sysdate as timestamp)), 3) / 24         H3
     , trunc(sysdate, 'hh24') - mod(EXTRACT(hour FROM cast(sysdate as timestamp)), 6) / 24         H6
     , trunc(sysdate, 'hh24') - mod(EXTRACT(hour FROM cast(sysdate as timestamp)), 8) / 24         H8
     , trunc(sysdate, 'hh24') - mod(EXTRACT(hour FROM cast(sysdate as timestamp)), 12) / 24        H12
     , trunc(sysdate, 'dd')                                                                        DAY
     , trunc(sysdate, 'd')                                                                         WEEK
from dual
/

C’était pourtant pas si compliqué