RE: SQL Tunning

["Powell, Mark D" <mark.powell@xxxxxxx>]

Lex, I do not agree with your example.  I understand your point but Oracle
has supported using + and - of a number or simple numeric expression as long
as I can remember:

UT1 > l
  1  select to_char(trunc(sysdate),'YYYYMMDD HH24:MI:SS') as D1,
  2   trunc(sysdate) - 22/86400 as D2
  3* from dual
UT1 > /

D1                D2
----------------- ---------
20040803 00:00:00 02-AUG-04

Looks like Oracle handles it correctly.  We have used this syntax from 6.36
to now, 9.2.0.4 on AIX 5.2.  I think we need to see the real SQL and Oracle
error to know what problem Wes was encountering.

HTH -- Mark D Powell --

-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx]On Behalf Of Lex de Haan
Sent: Tuesday, August 03, 2004 12:01 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: RE: SQL Tunning


you get errors because you cannot divide a DATE by a NUMBER --
trunc(sysdate) returns a DATE, and a DATE minus a NUMBER returns a DATE
again.
so you can only do things like:
trunc(sysdate) - (22/86400)

Kind regards,
Lex.

---------------------------------------------
visit my website at http://www.naturaljoin.nl
---------------------------------------------



-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx]On Behalf Of Wes Brooks
Sent: Tuesday, August 03, 2004 16:54
To: oracle-l@xxxxxxxxxxxxx
Subject: Re: SQL Tunning


Hello expert,

Thank you very much for all of your reply.

But in my case, the 1 is variable.  I tried the following but it complains
that

SELECT TRUNC(SYSDATE)-22/86400 from dual;

TRUNC(SYS
---------
02-AUG-04  <--- Wrong date.

SELECT TRUNC(SYSDATE-22)/86400 from dual;
SELECT (TRUNC(SYSDATE)-22)/86400 from dual;

These two SQL statements gave the error:

ORA-00932: inconsistent datatypes

If I try this one, it works.

SELECT TRUNC(SYSDATE - 22), TO_DATE(TO_CHAR(TRUNC(SYSDATE-22+1),
'DD-MON-YYYY HH24:MI:SS'),
'DD-MON-YYYY HH24:MI:SS') from dual;

Is there any way to improve this lengthly statement?

Thanks,
Wes



--- Edgar Chupit <edgar.chupit@xxxxx> wrote:

> Hello Wes,
>
> WB>    WHERE TRUNC(last_update_date) = TRUNC(SYSDATE - 1)
> WB> How to improve the performance?  Do I need to create a new index field
on the table with
> TRUNC(last_update_date)?
>
> You have several opportunities:
> a) you can rewrite your query to this:
>        where last_update_date between trunc(sysdate)-1 and
trunc(sysdate)-1/86400
> b) you can create function based index like:
>        create index tt_idx on tt(trunc(last_update_date));
> c) you can add column to your table with values from
trunc(last_update_date)
>
> What option to choose mostly depends on your requirements.

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