I am using Oracle express database, and I would like to know how can I change the date formatting-
from dd-mm-yyyy to dd-mm-yyyy hh-mm. Also, I've heard something about alter session, but I don't know how to use it in Perl.
This is what I did so far:
my $sth = $dbh->prepare("INSERT INTO Perl
(A_FIELD,B_FIELD,C_FIELD,TIME_STAME)
VALUES
(?,?,?,TO_DATE(?,'DD/MM/YYYY HH24:MI'))");
Date fields in Oracle are not formatted for display - it's an internal format that you convert to/from on input/output. When you store a date in Oracle date datatype columns, you convert your character string to internal format by describing the date-time to the TO_DATE function with the format model string. Oracle interprets the character string to it's internal format. When you need to display the date, you do the reverse - you tell oracle how to display the date by again giving a format model, this time to the TO_CHAR function.
To illustrate with your example, you could convert dd-mm-yyyy to dd-mm-yyyy hh-mm without ever storing the value (I assume you meant to display hours-minutes. The format model for minutes is 'MI', since 'MM' is month):
SQL> SELECT TO_CHAR(TO_DATE('01-01-2020','DD-MM-YYYY'),'DD-MM-YYYY HH-MI') mydate
FROM DUAL;
MYDATE
----------------
01-01-2020 12-00
Note that with your example, the time portion of your date is not supplied on input, so it defaults to midnight. To store a time value in your date column, you must supply a time value in your input:
SQL> SELECT TO_CHAR(TO_DATE('01/01/2020 10:13','DD/MM/YYYY HH:MI'),'DD-MM-YYYY HH-MI') mydate
FROM DUAL;
MYDATE
----------------
01-01-2020 10-13
SQL>
Depending on what you're trying to do, the system date in Oracle can be obtained by a reference to the pseudo-column SYSDATE:
SQL> SELECT TO_CHAR(sysdate,'MM/DD/YYYY HH:MI:SS AM') dt1,
2 TO_CHAR(sysdate,'DD-MON-YYYY HH24:MI:SS') dt2
3 FROM dual;
DT1 DT2
---------------------- -----------------------------
07/01/2011 03:44:30 PM 01-JUL-2011 15:44:30
SQL>
So the roundabout answer to your question is that it entirely depends on what format your input date string is in. You convert that to Oracle's date type via a format model and the TO_DATE function, then convert the date item to a display format of your choosing via TO_CHAR and a format model. As for the "ALTER SESSION" command you alluded to in your question, you can specify a default format model for date conversions by specifying the NLS_DATE_FORMAT parameter in the ALTER SESSION command:
SQL> SELECT sysdate FROM dual;
SYSDATE
---------
02-JUL-11
SQL> ALTER SESSION SET nls_date_format='dd-mon-yyyy hh24:mi:ss';
Session altered.
SQL> SELECT sysdate FROM dual;
SYSDATE
--------------------
02-jul-2011 10:39:24
If the incoming date string is in mm-yyyy format, then you can use the statement below(TO_DATE(?,'MM-YYYY')) to convert the string to date:
$sth = $dbh->prepare("INSERT INTO Perl (A_FIELD,B_FIELD,C_FIELD,TIME_STAME) VALUES (?,?,?,TO_DATE(?,'MM-YYYY'))");
Related
I want to convert a given timestamp in such format: 2019-04-08 00:00:00.0 to a date in this format: 2019-04-08.
I have already tried using:
SELECT TO_DATE('2019-04-20 00:00:00.0','YYYY-MM-DD') from dual;
But I got prompted with:
ORA-01830: date format picture ends before converting entire input
string
I think you may have some conceptual misunderstanding about how the TO_DATE function works, and also about how dates are processed by the DBMS.
YYY-MM-DD does not match the format of the actual string you're importing (2019-04-20 00:00:00.0) That's what the error is telling you. You must tell the TO_DATE function what to expect in the date string you input into it. You do that by means of the format string. if you don't specify a format string which matches the format you're actually going to supply, then the function will fail to process the string.
Next, you say you want to convert it "to a date in this format"...but this does not entirely make sense. TO_DATE converts a string into a variable of type DATETIME - i.e. a date object. A date object does not not exist in any particular format, it exists as an object. Internally it will store the date information in a way which is independent of any human-readable date format. The format relates entirely to the presentation of the date when seen as a string. Once you have a date object, you can then output the date in a particular format if you want to a human to be able to read it in the style that their culture is familiar with.
So, firstly to import your date string correctly as a date object, you can use an accurate format string, an also use TO_TIMESTAMP instead of TO_DATE so that it captures the sub-seconds value:
SELECT TO_TIMESTAMP('2019-04-20 00:00:00.0','YYYY-MM-DD HH24:MI:SS.FF5') from dual;
If you run this in a console the SELECT will then automatically re-format that date object (the result of the TO_DATE function) into the default date format configured in your server / session.
However if you actually want to see it on screen in a particular format, you can explicitly say so - a sensible way is using the TO_CHAR function:
SELECT TO_CHAR(TO_TIMESTAMPT('2019-04-20 00:00:00.0','YYYY-MM-DD HH24:MI:SS.FF5'), 'YYYY-MM-DD') from dual;
The full list of format specifiers can be found here (and in other places online as well).
Live demo of the above here: https://dbfiddle.uk/?rdbms=oracle_18&fiddle=619d918ea73953e11b3150c6b560112c
Assuming the input is actual text, and not a real timestamp, you could try just truncating the text before you call TO_DATE:
WITH cte AS (
SELECT '2019-04-20 00:00:00.0' AS ts FROM dual
)
SELECT TO_DATE(SUBSTR(ts, 1, 10), 'YYYY-MM-DD')
FROM cte;
If your input is an actual Oracle timestamp, and you want to convert it to a date, then you may use CAST:
SELECT CAST(ts AS DATE) dt
FROM cte;
Would CAST do any good?
I'm setting date format so that it displays time component, although it is 00:00:
SQL> alter session set nls_date_format = 'dd.mm.yyyy hh24:mi:ss';
Session altered.
SQL> select cast(timestamp '2019-04-20 00:00:00.0' as date) result from dual;
RESULT
-------------------
20.04.2019 00:00:00
Another format (without time component):
SQL> alter session set nls_date_format = 'dd.mm.yyyy';
Session altered.
SQL> select cast(timestamp '2019-04-20 00:00:00.0' as date) result from dual;
RESULT
----------
20.04.2019
SQL>
Or, using TO_CHAR function (so that session's date format doesn't matter):
SQL> select to_char(timestamp '2019-04-20 00:00:00.0', 'dd.mm.yyyy') result from dual;
RESULT
----------
20.04.2019
SQL>
I have an Oracle DB, and I don't control the date format. I want to know what the date format is to ensure that searches like
select * from search where search_date>='03/16/2016 00:00:00'
work as expected.
Don't do that - you are relying on implicit data type conversion which is going to fail at some point.
You have two options:
1) Use a proper ANSI SQL date literal:
select *
from search
where search_date >= timestamp '2016-03-16 00:00:00';
2) use to_date() (or to_timestamp()) and use a custom format.
select *
from search
where search_date >= to_date('03/16/2016 00:00:00', 'mm/dd/yyyy hh24:mi:ss');
With to_date() you should avoid any format that is language dependent. Use numbers for the month, not abbreviations (e.g. 'Mar' or 'Apr') because they again rely on the client language.
More details can be found in the manual: https://docs.oracle.com/cd/E11882_01/server.112/e41084/sql_elements003.htm#SQLRF51062
Never rely on implicit data type conversion.
You can get all the NLS session parameters with the query:
SELECT * FROM NLS_SESSION_PARAMETERS;
or, if you have the permissions GRANT SELECT ON V_$PARAMETER TO YOUR_USERNAME;, you can use the command:
SHOW PARAMETER NLS;
If you just want the date format then you can do either:
SELECT * FROM NLS_SESSION_PARAMETERS WHERE PARAMETER = 'NLS_DATE_FORMAT';
or
SHOW PARAMETER NLS_DATE_FORMAT;
However, you could also use ANSI date (or timestamp) literals which are format agnostic. An ANSI date literal has the format DATE 'YYYY-MM-DD' and a timestamp literal has the format TIMESTAMP 'YYYY-MM-DD HH24:MI:SS.FF9'. So your query would be:
select * from search where search_date>= DATE '2016-03-16'
or
select * from search where search_date>= TIMESTAMP '2016-03-16 00:00:00'
What is Oracle's Default Date Format?
A DATE doesn't have any format. Oracle does not store dates in the format you see. It stores it internally in 7 bytes with each byte storing different components of the datetime value.
Byte Description
---- -------------------------------------------------
1 Century value but before storing it add 100 to it
2 Year and 100 is added to it before storing
3 Month
4 Day of the month
5 Hours but add 1 before storing it
6 Minutes but add 1 before storing it
7 Seconds but add 1 before storing it
To display, use TO_CHAR with proper FORMAT MODEL.
For comparing, use TO_DATE with proper FORMAT MODEL.
What you see as a format by default, is your locale specific NLS settings.
SQL> select parameter, value from v$nls_parameters where parameter='NLS_DATE_FORMAT';
PARAMETER VALUE
--------------- ----------------------------------------------------------------
NLS_DATE_FORMAT DD-MON-RR
SQL> select sysdate from dual;
SYSDATE
---------
17-MAR-16
SQL> select to_char(sysdate, 'mm/dd/yyyy hh24:mi:ss') from dual;
TO_CHAR(SYSDATE,'MM
-------------------
03/17/2016 12:48:41
SQL>
search_date>='03/16/2016 00:00:00'
You are comparing a DATE with a string literal. Always, explicitly convert the string into date using TO_DATE and proper format mask.
TO_DATE('03/16/2016', 'MM/DD/YYYY')
Or, if you dealing only with the date part and not concerned with the time portion, then use the ANSI date literal which uses a fixed format DATE 'YYYY-MM-DD'
DATE '2016-03-16'
You might just be lucky to get an output due to an implicit datatype conversion based on your locale specific NLS settings. Never ever rely on implicit datatype conversion, it might work for you, might fail for others where the nls settings are different.
I have a date field in a table that contains date in dd-MMM-yy format .
I want to create a function that get this date check it for not null and then change it to yyyy/mm/dd format
but the problem is that oracle doesn't accept dd-MMM-yy formate date as a input parameter and
it say : Please Use yyyy-MM-dd date format !!!
how can I first change dd-MMM-yy formate to yyyy-MM-dd so oracle accept it as input then change it to yyyy/mm/dd
: Please Use yyyy-MM-dd date format !!!
That is no way related to an Oracle error.
I have a date field in a table that contains date in dd-MMM-yy format .
No, you are confused. Oracle does not store dates in the format you see. It stores it internally in 7 bytes with each byte storing different components of the datetime value.
Byte Description
---- -------------------------------------------------
1 Century value but before storing it add 100 to it
2 Year and 100 is added to it before storing
3 Month
4 Day of the month
5 Hours but add 1 before storing it
6 Minutes but add 1 before storing it
7 Seconds but add 1 before storing it
If you want to display, use TO_CHAR with proper FORMAT MODEL.
While inserting, use TO_DATE with proper FORMAT MODEL.
What you see as a format by default, is your locale specific NLS settings.
SQL> select parameter, value from v$nls_parameters where parameter='NLS_DATE_FORMAT';
PARAMETER VALUE
--------------- ----------------------------------------------------------------
NLS_DATE_FORMAT DD-MON-RR
SQL> select sysdate from dual;
SYSDATE
---------
03-FEB-15
SQL> select to_char(sysdate, 'mm/dd/yyyy hh24:mi:ss') from dual;
TO_CHAR(SYSDATE,'MM
-------------------
02/03/2015 17:59:42
SQL>
Update Regarding MMM format.
By MMM if you mean the month name up to three characters, then use MON.
I'm trying to convert string column to date in Oracle SQL.
Here is my an example of value from the data:
'03/12/14 11:00:00'
Here is my query:
select to_date(A,'DD/MM/YY HH24:MI:SS')
from MyTable
Here is an example of the output:
03-DEC-14
Why my query return only the date but not the hour?
Assuming you are using SQL*Plus (or SQL Developer) the default NLS_DATE_FORMAT is applied when a DATE value is displayed. To verify your current format you can run:
select value
from nls_session_parameters
where parameter = 'NLS_DATE_FORMAT';
To adjust this, run:
alter session set nls_date_format = 'YYYY-MM-DD HH24:MI:SS';
Then you should see the time as well.
You are trying to DISPLAY the datetime value. Use TO_CHAR along with proper FORMAT MODEL.
For example,
select to_char(sysdate, 'mm/dd/yyyy hh24:mi:ss') from dual;
A DATE consists of both date and time portions. You just need to make sure you use appropriate format model to display it. Else, you end up with a format which depends on your locale-specific NLS settings.
You can use timestamp
select to_timestamp(A, 'DD/MM/YY HH24:MI:SS') from MyTable
If you want a query that returns the time portion of the date without having to alter the nls_date_format you can convert the date you got from the to_date function to a text representation (the default text representation is dd-Mon-yy as you found out) like this:
select to_char(
to_date(A,'DD/MM/YY HH24:MI:SS'),
''DD/MM/YY HH24:MI:SS')
from MyTable;
Ideally, column A of MyTable should have been defined as a date column instead of a varchar2 column. There are several reasons to do that; data integrity, and better SQL optimization.
I've trawled the SO website thinking this is pretty obvious but alas I have not found one yet.
Basically the setup is as follows:
I have a string in a table like so:
06/22/2010 00:00:00
I do a select on it:
SELECT To_Date(item, 'MM/DD/YYYY HH24:MI:SS') from that_table
so that effectively I am doing
SELECT To_Date('06/22/2010 00:00:00', 'MM/DD/YYYY HH24:MI:SS') from that_table
My database returns:
22.06.2010 00:00:00
Now I know I can do a
to_char(to_Date('06/22/2010 00:00:00', 'MM/DD/YYYY HH24:MI:SS'), 'MM/DD/YYYY HH24:MI:SS')
but I need the select to return a date format (MM/DD/YYYY HH24:MI:SS), not a string. How can I do that?
Edit:
Real output:
22.06.2010 00:00:00
Desired output (in Date format):
06/22/2010 00:00:00
A DATE doesn't have a format, it is only formatted when converted to a character string for display purposes. If you are using SQL Plus then when you display a DATE column (without using TO_CHAR to explicitly format it), SQL Plus itself performs a TO_CHAR conversion using the NLS_DATE_FORMAT setting:
SQL> select sysdate from dual;
SYSDATE
---------
23-JUN-10
SQL> alter session set nls_date_format = 'YYYY-MM-DD HH24:MI:SS';
Session altered.
SQL> select sysdate from dual;
SYSDATE
-------------------
2010-06-23 15:17:12
If you are not using SQL Plus, then whatever tool you are using will be doing something similar and may have a different way to specify the date format for display.
a Date is a point in time, it has no format (like numbers: they don't have format). When you display the date, obviously it has to get a format: if you don't specifically give Oracle a format, the default format for your session will be used (session parameter NLS_DATE_FORMAT).
In consequence: use the DATE datatype for date arithmetics and storage (no format). Use the to_char function or something equivalent when you need to display the date (in a report or in the GUI).