select TRUNC(TO_DATE('22-AUG-03'), 'YEAR')
from dual;
ORA-01843: not a valid month
1st example -> https://www.techonthenet.com/oracle/functions/trunc_date.php
I know "trunc" function takes in a date and optional fmt parameter.
Why am I getting this error?
I don't think the problem is trunc(). I think the problem is the date format. You are safer using the date keyword and an ISO-standard formatted date:
select TRUNC(DATE '2003-08-22', 'YEAR')
from dual;
The interpretation of a date string depends on the internationalization settings for your particular environment. The above does not have that dependency.
Here is a very simple check: IN THE SAME SESSION where your SELECT fails, and WITHOUT you altering the NLS_DATE_FORMAT, see what happens if you run the simpler statement,
SELECT TO_DATE('22-AUG-03') FROM DUAL
You will get the same error - which proves conclusively that it has nothing to do with TRUNC().
To make everything work exactly as in the tutorial, issue the command
ALTER SESSION SET NLS_DATE_FORMAT = 'dd-MON-yy'
first, before everything else. Note though that formats that have the year as two digits instead of four are a very bad idea in most cases.
It seems that you want to get the year of the date you receive in parameter
If you get '22-AUG-03' as parameter, add to TO_DATE function the date format you expect and then trunc it:
SELECT TRUNC(TO_DATE('22-AUG-03', 'dd-MON-yy'),'YEAR') FROM DUAL
Use SELECT EXTRACT(YEAR FROM TO_DATE('22-AUG-03', 'dd-MON-yy')) FROM DUAL;
to extract year from date.
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;
Am at the end of my tether so hoping someone can help me! I'm really new to Oracle, but do have a SQL background which is why I'm finding this so frustrating!
We have a system that runs Oracle at the back end. I've got very limited access to the system and can only write select queries.
I've written a query that gets the data I want but the date format is coming out as mm dd yyyy what I need is dd/mm/yyyy
I ran SELECT sysdate FROM dual and that come back as:
SYSDATE
03 11 2015
So my select statement reads (action_date is the column in question)
Select username, action_date from adminview
I've tried everything I can think of to change the date format including:
to_date(action_date,'dd/mm/yyyy')
to_date(action_date,'dd/mm/yyyy','nls_language=English')
to_date(to_date(action_date,'mm dd yyyy'),'dd/mm/yyyy')
I've also tried to_char along the same lines.
If you want to format a DATE value, use TO_CHAR():
SELECT username, TO_CHAR(action_date, 'DD/MM/YYYY') AS action_date
FROM adminview;
If it's not a DATE value, then you'll want to convert it to a DATE (based on what it currently looks like), then use TO_CHAR() to format.
select to_date('07/09/14','yyyy-mm-dd') from dual;
is returning 14-SEP-07
I was expecting it to thrown an exception as the date and the format requested are not the same. Secondly we have slashes in the input date and hypen in the format.
Can someone tell me how to confirm if the input value is of the provided format.
to_date is relatively liberal in attempting to convert the input string using the provided format mask. It generally doesn't concern itself with the specific separator character in the string or in the format mask-- your string could use dashes or slashes or, heck, asterixes if you wanted. Of course, that can mean that you get unexpected results. In this case, for example, the date that is created is in the year 7 (i.e. 2007 years ago). That is a valid date in Oracle but it is highly unlikely to be the date you expect unless you're storing data about ancient Rome.
What, exactly, does it mean to you to "confirm if the input value is of the provided format"? Depending on what you are looking for, you may want to use regular expressions.
REGEXP_LIKE can somewhat do this. Note, this is basic, since it would accept values like 2014-0-32. However, those insane values would fail in whatever you do next in your code, such as to_date().
SELECT 'Yes, valid boss.' is_valid FROM DUAL
WHERE regexp_like('07/09/14','^[0-9]{4}-[0-9]{1,2}-[0-9]{1,2}$');
no rows selected
.
SELECT 'Yes, valid boss.' is_valid FROM DUAL
WHERE regexp_like('2014-07-09','^[0-9]{4}-[0-9]{1,2}-[0-9]{1,2}$');
IS_VALID
----------------
Yes, valid boss.
.
SELECT 'Yes, valid boss.' is_valid FROM DUAL
WHERE regexp_like('2014-7-9','^[0-9]{4}-[0-9]{1,2}-[0-9]{1,2}$');
IS_VALID
----------------
Yes, valid boss.
EDIT: and if you're into PL/SQL, you can do a regex match and throw your own exception ...
DECLARE
v_is_valid INTEGER;
BEGIN
SELECT count(*) INTO v_is_valid FROM DUAL
WHERE regexp_like('07/09/14','^[0-9]{4}-[0-9]{1,2}-[0-9]{1,2}$');
IF v_is_valid = 0 THEN
raise_application_error (-20400, 'Exception: date was given in the wrong format.');
END IF;
END;
/
*
ORA-20400: Exception: date was given in the wrong format.
TO_DATE() only takes a string and convert it to a date/time in respect to the given format your provided. If it can't find the exact format, it will do its best to determine what could it be. Given your 'yyyy-mm-dd' format, Oracle deduces that the 07 is the year, and the 14 is the day.
You have to write your own function to throw an expected exception or the like to handle the issue, if there is any based on your functional requirements.
So when you select the resulting date, the format that is displayed is actually based on your NLS_DATE_FORMAT system parameter, which gives your resulting date.
I'm using this sql query:
select sysdate, sysdate - INTERVAL '6' month from dual;
But it is return: ORA-01839: date not valid for month specified.
Which is weird, because if I change the the number into 9, it is return the date (sysdate = 31/05/11 and the subtracted is 31/08/10). I'm also tried using different value: 1,3,6,8,11 also not working, but 2,4,5,7,9,12 are working.
From the numbers, I think it is because the resulting quert doesn't have 31 days for that month. Is this the expected behavior? Because in MySQL, I can use the query (select now() - Interval 6 Month;) to get the correct value. Is there any other way?
I am using Oracle 11.1.0.6
It is the expected behaviour; see the sixth bullet in the datetime/interval arithmetic section of the documentation.
As Lisa says you can use add_months, which has the opposite behaviour - which can also cause confusion sometimes. You need to decide which is most suitable for you.
select sysdate,add_months(sysdate,-6) from dual;
I have to query all_objects table where last_ddl_time='01 jan 2010' but it refuses the date format...
Any body give me the exact format to query?
As AKF said, you should be using Trunc unless you know the exact time the DDL was modified. Your query you added in the comments is looking for any objects where the DDL changed at 1/1/2010 00:00:00. Try:
SELECT *
FROM all_objects
WHERE trunc(last_ddl_time) = to_date('01-01-2010','dd-mm-yyyy');
I suggest you to use de date literal:
where trunc(last_ddl_time) = date '2010-01-01'
You can use the to_date function to format your date. If you enter a literal string, Oracle will attempt to convert that string using to_date with a default format 'DD-MON-YY', so your date would look like "01-JAN-10". As Oracle will be using this same function, you might want to put it in yourself and enjoy the finer granularity that custom formatting can provide.
It would be good to note that the dates stored in that column most likely have more precise dates, including hours and minutes, etc. Though you will be taking a bit of a performance hit, you might be better served using trunc(last_ddl_time) if you are testing with =.
There is some good info on Dates in Oracle at this link.
SELECT *
FROM all_objects t
WHERE trunc(t.last_ddl_time, 'DD') = to_date('2010-JAN-01', 'YYYY-MON-DD');