Hi,

for creating a unique index with a date-column A_DATE I'm using a
calculated column X_DATE as (trunc(A_DATE)):

CREATE UNIQUE INDEX UX_A_TABLE
ON A_TABLE (
...,
X_DATE
)
/

Using A_DATE in UX_A_TABLE would fail if someone would use sysdate two
times a day.
Is there a column-data-type restricted to truncated date format?


--
Norbert
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit
Production

On Apr 12, 6:22*am, Norbert Winkler <norbert.winkl... (AT) gmx (DOT) de> wrote:
There is DATE and TIMESTAMP data types. Oracle has always had the
combined date/time type. There is no truncated date type. What's
stopping you from using a check constraint?

Ed

On Apr 12, 6:22*am, Norbert Winkler <norbert.winkl... (AT) gmx (DOT) de> wrote:
Normally indexes on date columns are non-unique but if you want to
restrict a user to only one entry per day then using trunc(sysdate)
would result in a time of midnight. All date columns always have a
time component. However I think you would need composite index on
user and date if you want to perform this test per user.

Either a column constraint or perhaps a before insert trigger that
truncates the input date value might suite your need.

HTH -- Mark D Powell --

On 04/12/2010 04:54 PM, Mark D Powell wrote:
Err, doesn't that depend on the index definition? I don't see any
general rule that would make indexes specifically on DATE columns non
unique. Or did you mean that usually people define non unique indexes
on DATE columns?

What user? Am I missing something from the original question?

I assume, with the constraint you would ensure that each DATE inserted
would be a truncated one.

Cheers

robert

--
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

On Apr 12, 1:57*pm, Robert Klemme <shortcut... (AT) googlemail (DOT) com> wrote:
For one of my systems, and of course I haven't made sure that the
requirement for date is met:

1 select uniqueness,count(*) from dba_indexes a,dba_ind_columns b
2 where a.index_name=b.index_name
3 and a.owner=b.index_owner
4 and b.column_name like '%_DATE%'
5* group by uniqueness
SYS@TTST> /

UNIQUENES COUNT(*)
--------- ----------
NONUNIQUE 34
UNIQUE 213

I think I agree with where Mark is coming from, though, if he is
assuming primary key v. other keys. This system is kinda weird that
way for an ERP/MRP.

The original question was kind of ambiguous, perhaps Norbert could
tell us what he is trying to do rather than how to do something
mysterious.

jg
--
@home.com is bogus.
http://www.infoworld.com/print/119525

Norbert Winkler <norbert.winkler1 (AT) gmx (DOT) de> writes:

No. I guess you could create a table of dates, maybe call it day, and
then make its PK the date truncated. Pre-populate it with the days that
can happen, and then make your "day" columns children of that domain
set.

Don't understand how having the datatype would solve this issue.

--
Galen Boyer

--- news://freenews.netfront.net/ - complaints: news (AT) netfront (DOT) net ---

Am Mon, 12 Apr 2010 06:31:35 -0700 (PDT) schrieb Ed Prochak:

approach with the most benefit.

--
Norbert
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit
Production

On Apr 12, 5:39*pm, joel garry <joel-ga... (AT) home (DOT) com> wrote:
My comment that most indexes on date columns are non-unique is in
reference to single column indexes which is what I believe Norbert was
asking about. In my experience it is rarely logical for single column
indexes on date data types to be unique even if if is possible.

Looking back at the sample code it appears that the index is probably
multi-column and so a unique index on trunc(sysdate) would limit the
table to one row per set of remaining key column values per day. Even
with update from Norbert I cannot tell if we answered his question
fully or not.

Mark D Powell