What's the best way to get a timestamp that consists of the actual date but a fixed time part in oracle.
e.g.Today and always 09:00:00
2020-10-20 09:00:00
in MSSQL I would use FORMAT(GETDATE(),'yyyy-MM-dd 09:00:00')
Assuming you want a date rather than a varchar2, I'd use
trunc(sysdate) + interval '9' hour
trunc(sysdate) returns today at midnight and then interval '9' hour adds 9 hours to give you 9am. You can also add fractions of a day to a date so you could say
trunc(sysdate) + 9/24
I tend to find the interval notation more self-explanatory particularly if you're coming from a non-Oracle background.
You can use something like this:
SQL> alter session set NLS_DATE_FORMAT='YYYY-MM-DD';
Session altered.
SQL> set head off
SQL> select sysdate||' 09:00:00' from dual;
2020-10-19 09:00:00
Hope this is what you were looking for :)
Related
I'm trying to run this queries (Oracle 12c):
SELECT trunc(sysdate) - '25-SEP-18' FROM dual;
SELECT 1 FROM dual WHERE trunc(sysdate) = '04-SEP-19';
CREATE TABLE my_table (order_date date);
INSERT INTO my_table (order_date) VALUES ('04-SEP-19');
I expect implicit conversion and everything is good with the 2 last queries, but for the first i get error ORA-01722: invalid number. NLS_DATE_FORMAT = 'DD-MON-RR'. What is the problem?
The question is WHY is does not work? I didn't find any explanations in documentation.
The documentation has a section on Datetime/Interval Arithmetic which explains what is allowed. The table shows that arithmetic is only allowed between dates, timestamp, intervals and numbers. When you do:
SELECT trunc(sysdate) - '25-SEP-18'
you are trying to subtract a string from a date, which isn't possible. Oracle 'helpfully' tries anyway and interprets the string as a number, effectively doing:
SELECT trunc(sysdate) - to_number('25-SEP-18')
which understandably throws the error you see, "ORA-01722: invalid number". As already said, you should explicitly convert your string to a date:
SELECT trunc(sysdate) - to_number('25-SEP-18', 'DD-MON-RR')
or preferably with a four-digit year, and since you're using a month name it's safer to specify the language that is in:
SELECT trunc(sysdate) - to_number('25-SEP-2018', 'DD-MON-YYYY', 'NLS_DATE_LANGUAGE=ENGLISH')
or more simply, if it's a fixed value, with a date literal:
SELECT trunc(sysdate) - DATE '2018-09-25'
I expect implicit conversion
You should not rely on implicit conversion, particularly where that is influenced by session NLS settins. As well as the date language I already mentioned, someone else running your statement could have a different NLS_DATE_FORMAT setting which could lead to errors or more subtle data mismatches or corruption; e.g.
alter session set nls_date_format = 'DD-MON-YYYY';
SELECT trunc(sysdate) - DATE '2018-09-25' FROM dual;
TRUNC(SYSDATE)-DATE'2018-09-25'
-------------------------------
344
SELECT trunc(sysdate) - to_date('25-SEP-18') FROM dual;
TRUNC(SYSDATE)-TO_DATE('25-SEP-18')
-----------------------------------
730831
SELECT 1 FROM dual WHERE trunc(sysdate) = '04-SEP-19';
no rows selected
CREATE TABLE my_table (order_date date);
INSERT INTO my_table (order_date) VALUES ('04-SEP-19');
The second query gets a much bigger value than expected; and the third gets no rows back from dual.
Looking at the implicitly converted date shows you why:
SELECT to_char(order_date, 'SYYYY-MM-DD HH24:MI:SS') FROM my_table;
TO_CHAR(ORDER_DATE,'
--------------------
0019-09-04 00:00:00
With a YYYY mask (and no FX modifier) a 2-digit year value like 19 is converted as 0019, not 2019. That sort of problem could go unnoticed for some time, giving you incorrect results in the meantime.
If the session's format mask had RRRR or - as you have - RR then it would be interpreted as 2019; but the point is that you usually have no control over the settings in another session that runs your code later.
You can also cause performance issues or errors by creating implicit conversions where you didn't expect, or where they behave in a way you didn't expect. Not in this example - "When comparing a character value with a DATE value, Oracle converts the character data to DATE" - but it still comes up. It's better to avoid the possibility.
When dealing with strings with dates in them you should use the to TO_DATE command, otherwise Oracle may not always figure out that the string contains a date.
SELECT trunc(sysdate) - TO_DATE('25-SEP-18') FROM dual;
Even better is to indicate the format of the date within the string
SELECT trunc(sysdate) - TO_DATE('25-SEP-18','DD-MON-RR') FROM dual;
I have a varchar column called begin_time that stores the 24-hour time as a varchar with no time formatting, ie 1330
I need to convert this varchar to a usable timestamp, datetime, etc. where I can easily convert the varchar to a standard time format (1:30 PM)
The end format type doesn't matter as long as I can convert the varchar into a format that I can manipulate to a standard format.
I've tried looking into Cognos-specific format tricks (These functions are for Metric Designer, and I'm using Report Studio) to no avail. The methods I found when looking for oracle-specific tricks seemed to be way too convoluted (using insanely long regex rules) for what I need.
If I need to have a date involved, I can use the column start_date and append the varchar time.
Note: start_date is in the date format
Example
select
to_date('08/27/2018','MM/DD/YYYY') as start_date
, '1300' as begin_time
from dual
What I ultimately need is just to be able to output the time as 1:00 PM
Any help would be appreciated. I'm beating my head against the wall on this... I'm used to using proprietary codes for periods of time and don't have a lot of experience with the true datetime formats.
Updates answering questions
Alex Poole, I make no claims that this system is the best... It's vendor-provided. :)
The BEGIN_TIME is always 4 characters
It does look like I was overthinking it quite a bit... Littlefoot may have nailed it on the head, but I unfortunately won't have a chance to test that until tomorrow.
Thank you all for the fast responses. I might have hair left when this request is over now :)
Final Thought
My lesson learned from this is simple: If you're dealing with time formats, don't throw out the idea of using a Date format function.
Looking for this?
SQL> with test (col) as
2 (select '1330' from dual)
3 select to_char(to_date(col, 'hh24mi'), 'hh:mi am') result
4 from test;
RESULT
--------
01:30 PM
SQL>
What does it do?
TO_DATE converts string you have (such as 1330) into a valid DATE value. By default, it'll be a date value truncated to the first of current month:
SQL> alter session set nls_Date_format = 'dd.mm.yyyy hh24:Mi';
Session altered.
SQL> select to_date('1330', 'hh24mi') res1 from dual;
RES1
----------------
01.04.2019 13:30
SQL>
applying TO_CHAR to it, again with the appropriate format mask, returns the desired result
Why
select trunc(to_date('23/06/2017','DD/MM/YYYY'), 'DAY') from dual;
returns
19.06.17
instead of expected
23.06.17?
We are on Oracle 11.
The DAY format returns the closest starting day of the week. Depending on your DB configuration, this might be a Sunday, Monday (in your case)...
You probably need the DD format instead.
Oracle doc
DAY truncates to closest SUNDAY [1]
you can use DD.
select trunc(to_date('23/06/2017','DD/MM/YYYY'), 'DD') from dual;
Your format is wrong, should be DD format:
select trunc(to_date('23/06/2017','DD/MM/YYYY'), 'DD') from dual;
Date Format Models for the ROUND and TRUNC Date Functions
DDD
DD
J
Day
I have a datetime column in Oracle (MM/DD/YYYY HH:MM:SS AM/PM) but when I do this:
SELECT MAX(D_DTM)-1 FROM tbl1
...it goes back a day. How do I remove one hour from the column rather than one day?
I've also noticed that the datetime records for 12AM look like MM/DD/YYYY and not MM/DD/YYYY 00:00:00; I'm not sure if that matters.
Randy's answer is good, but you can also use intervals:
SELECT MAX(D_DTM)- interval '1' hour FROM tbl1
yes - dates go by integer days.
if you want hours you need to do some math - like -(1/24)
Or use the INTERVAL function. It has the same result but I think it reads more clearly - that's of course just an opinion :)
SELECT MAX(D_DTM) - INTERVAL '1' HOUR FROM tbl1
The nice thing about the INTERVAL function is that you can make the interval be years, months, days, hours, minutes or seconds when dealing with a DATE value, though the month interval can be tricky when dealing with end-of-month dates.
And yes, the quote around the 1 in the example is required.
You can also use the Oracle-specific NumToDSInterval function, which is less standard but more flexible because it accepts variables instead of constants:
SELECT MAX(D_DTM) - NUMTODSINTERVAL(1, 'HOUR') FROM tbl1
select sysdate - numtodsinterval(1,'hour') from dual
Its simple.
sysdate - 5/(24*60*60) --> Subtracts 5 seconds from systime
sysdate - 5/(24*60) --> Subtracts 5 minutes from systime
sysdate - 5/(24) --> Subtracts 5 hours from systime
Hence
select (sysdate - (1/24)) from dual
Another method of using intervals is
NUMTODSINTERVAL( number, expression )
examples
NUMTODSINTERVAL(150, 'DAY')
NUMTODSINTERVAL(1500, 'HOUR')
NUMTODSINTERVAL(15000, 'MINUTE')
NUMTODSINTERVAL(150000, 'SECOND')
I bring this up because it is useful for situations where using INTERVAL wont work.
Probably a classic... Would you know a easy trick to retrieve an UTC value of SYSDATE on Oracle (best would be getting something working on the 8th version as well).
For now I've custom function :(
Cheers,
Stefan
You can use
SELECT SYS_EXTRACT_UTC(TIMESTAMP '2000-03-28 11:30:00.00 -02:00') FROM DUAL;
You may also need to change your timezone
ALTER SESSION SET TIME_ZONE = 'Europe/Berlin';
Or read it
SELECT SESSIONTIMEZONE, CURRENT_TIMESTAMP FROM dual;
select sys_extract_utc(systimestamp) from dual;
Won't work on Oracle 8, though.
Usually, I work with DATE columns, not the larger but more precise TIMESTAMP used by some answers.
The following will return the current UTC date as just that -- a DATE.
CAST(sys_extract_utc(SYSTIMESTAMP) AS DATE)
I often store dates like this, usually with the field name ending in _UTC to make it clear for the developer. This allows me to avoid the complexity of time zones until last-minute conversion by the user's client. Oracle can store time zone detail with some data types, but those types require more table space than DATE, and knowledge of the original time zone is not always required.
I'm using:
SELECT CAST(SYSTIMESTAMP AT TIME ZONE 'UTC' AS DATE) FROM DUAL;
It's working fine for me.
If you want a timestamp instead of just a date with sysdate, you can specify a timezone using systimestamp:
select systimestamp at time zone 'UTC' from dual
outputs: 29-AUG-17 06.51.14.781998000 PM UTC