store dates in oracle - sql

I have a table as
create table Dummy (date_created date)
in oracle.I want to store date in 'dd-mon-yyyy' (12-dec-2010) format.
How should i do this.
Please help.

In Oracle a column created with the DATE datatype just stores the date. It doesn't have a particular format, it just stores the day, month, year, hour, minute, and second. You need to convert from whatever format you have using the TO_DATE function. If you have a text string with the date in 'dd-mon-yyyy' format and you want to put this date into your table you'd use something like
INSERT INTO DUMMY (DATE_CREATED)
VALUES (TO_DATE('01-FEB-2011', 'DD-MON-YYYY');
Going the other way (from DATE column value to character string) you'd use the TO_CHAR function. If you were retrieving a value from your table and wanted to convert it to 'DD-MON-YYYY' format you'd use something like
SELECT TO_CHAR(DATE_CREATED, 'DD-MON-YYYY')
FROM DUMMY;
Share and enjoy.

Use to_date() function. In your case, the syntax would be
insert into Dummy values (to_date('08-09-2010', 'dd-mm-yyyy'));
Here is a link to the detailed help.

The DATE datatype will store date and time information (century, year, month, day, hours, minutes, and seconds) in an internal format in the database. When you get it out of the database, you can choose to display it in whatever format you like.
This information is either created using implicit conversion from a string or explicitly using either the TO_DATE function or the ANSI date literal. If you look in the v$nls_parameters view, this will tell you what the NLS_DATE_FORMAT is which is generally used for the implicit conversion. This may often be defined as DD-MON-RR, which might be why the date will come out as 23-DEC-10 when the query select sysdate from dual is run. (Not entirely sure I'm right about the nls stuff. Correct me if I'm wrong.)
However, all the date information is available if you know how to get it. The query select to_char(sysdate, 'dd-mon-yyyy hh24:mi:ss') from dual will return all the date fields.
Likewise, the insert statement shown below will create a row with a date value in it.
insert into dummy (date_created)
values (to_date('12-dec-2010 12:34:56', 'dd-mon-yyyy hh24:mi:ss'))`
This data can then be retrieved.
select date_created from dummy
This will implicitly convert the date to a character string using the NLS_DATE_FORMAT, providing the output below.
DATE_CREA
---------
23-DEC-10
The full date information is available by explicitly converting the date to a character string.
select to_char(date_created, 'DD-MON-YYYY') as date_created from dummy;
select to_char(date_created, 'DD-MON-YYYY HH24:MI:SS') as date_created
from dummy;
This will provide output in the format you require:
DATE_CREATE
-----------
23-DEC-2010
If you always use the TO_DATE and TO_CHAR functions to convert to/from a date datatype, then you will have fewer problems. Implicit conversion is useful but can cause some confusion or problems.

You can keep and eye here
http://www.techonthenet.com/oracle/functions/to_date.php
use to_date function to save a data with the format you need. I suggest to use SYSDATE updating table and when you need to read data from table use something like that:
dbms_output.put_line(TO_CHAR(SYSDATE, 'DD-MON-YYYY HH24:MI:SS'));
to solve your problem use:
to_date('08/JAN/2010', 'DD/MON/YYYY')

Just use TRUNC(YourDate) if date have time part, it will be truncate time part. Oracle have not just 'DATE' type, 'DATE' always have time part.
However if you do not specify time - it will 00:00:00.
SELECT TRUNC(SYSDATE) from dual
Result:
23-12-2010

Oracle does not support DATE without time part.
You can make it always be an integer date by adding a CHECK constraint:
CREATE TABLE dummy (date_created date CHECK (date_created = TRUNC(date_created)))
, insert it in any format you want:
INSERT
INTO dummy (date_created)
VALUES (TO_DATE('23-DEC-2010', 'dd-mon-yyyy'))
and select it in any format you want:
SELECT TO_CHAR(date_created, 'dd-mon-yyyy')
FROM dummy

Related

Oracle convert Timestamp to Date

I have date like :
2020/05/09T02:40:03
2020/05/16T02:40:03
2020/05/15T02:40:03
I need to convert it into Date format 'dd/mm/yyyy'.
My query
select cast(date_registered as date) as Reg_date from employee
Error:
Literal does not match format string
Note:I have also used TO_Char , TO_Date but not working
First, what you tried to convert to date is not a timestamp, it is a string.
Second, cast(... to date) does not take a format model - it simply relies on your session nls_date_format parameter, which doesn't match the string's date format. (Especially the boilerplate, hard-coded T in the middle, which has no meaning in Oracle.)
You need to_date() with an appropriate format model. Notice the handling of hardcoded string fragments (they appear in double-quotes in the format model).
select to_date(date_registered, 'yyyy/mm/dd"T"hh24:mi:ss') as reg_date
from employee;
In Oracle, a date data type is always stores as 7-bytes consisting of century, year-of-century, month, day, hours, minutes and seconds; so, asking to convert something that has year-to-seconds components to a date does not require you to do anything:
SELECT date_registered AS reg_date FROM employee
Now, if you are storing date_registered as a string data type rather than as a date data type then you need to convert using TO_DATE:
SELECT TO_DATE( date_registered, 'YYYY-MM-DD"T"HH24:MI:SS' ) AS reg_date
FROM employee
However, you should not do this and you should fix the underlying problem that you are storing dates as strings and not dates. You can solve this by converting the data type of the column:
ALTER TABLE employee ADD ( date_registered2 DATE );
UPDATE employee
SET date_registered2 = TO_DATE( date_registered, 'YYYY-MM-DD"T"HH24:MI:SS' );
ALTER TABLE employee DROP COLUMN date_registered;
ALTER TABLE employee RENAME COLUMN date_registered2 TO date_registered;
(Note: The queries below assume that you have "fixed" the table so that the date_registered column has the date data type; if you do not want to do this then you will need to include the TO_DATE conversion as well.)
If you want the output to be a date where the time component is truncated back to midnight then:
SELECT TRUNC( date_registered ) AS reg_date
FROM employee
(Note: The displayed date will still have hours, minutes and seconds components but they will all be zero after being passed through TRUNC.)
If you want it in a specific format, without the time component, then you need to output it as a formatted string (since the date data type does not have an associated format) using TO_CHAR:
SELECT TO_CHAR( date_registered, 'DD/MM/YYYY' ) AS reg_date
FROM employee
db<>fiddle here

Converting timestamp to date in Oracle 12c

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>

Oracle to_timestamp

quick question on Oracle To_timestamp.
I have a two fields in a table that are both varchars
1 field contains the YYYYMMDD formatted value
the 2nd field contains the hh24mmss formatted value
Im trying to convert these two fields into a timestamp field,
expected output is DD/MM/YYYY HH24:mm:ss
like '7/23/2015 12:53:04'
however, it gaves me weird result...
like '7/15/0023 12:53:04'
seems year becomes day and day becomes year..
---------- heres my sql ----------------
select
to_date(to_char(to_date('20150723','yyyymmdd'),'yyyymmdd'),'yyyymmdd') dt,
to_char(to_date(SUBSTR('005304000',1,6), 'hh24miss'), 'hh24:mi:ss') tm,
TO_TIMESTAMP(
to_date(to_char(to_date('20150723','yyyymmdd'),'yyyymmdd'),'yyyymmdd') ||
to_char(to_date(SUBSTR('005304000',1,6), 'hh24miss'), 'hh24:mi:ss'), 'yyyy/mm/dd HH24:MI:SS' ) dttm
from dual
You have one layer to much in your conversion chain. And it will be much easier if you concatenate the two columns before converting them:
to_date(date_column||time_column, 'YYYYMMDDHH24MISS')
will return a date and a time (an Oracle DATE includes a time part).
Now that you have a proper date value, you can then format that as you want:
to_char(to_date(date_column||time_column, 'YYYYMMDDHH24MISS'), 'yyyy/mm/dd HH24:MI:SS')
As your "time" column doesn't contain milliseconds there is no real benefit in using to_timestamp.
But you should really fix your table, and store that information in a single DATE (or TIMESTAMP) column. Storing dates in varchar columns is always a very bad choice.

ORA-01722 INVALID NUMBER in oracle

I am getting invalid number error message while executing the below select statement.Can any one have an idea about the issue..Please let me know.
select TO_DATE(TO_CHAR('2015/01/22 00:00:00','YYYY/MM/DD'),'YYYY/MM/DD')
actually i want oracle standard date format without time stamp for this date '2015/01/22 00:00:00'
select to_date('2015/01/22 00:00:00','YYYY/MM/DD HH24:MI:SS') as dt
from dual
Fiddle - http://sqlfiddle.com/#!4/6a3a6/1/0
As an FYI, the Oracle DATE data type does include the time component (just not down to fractional seconds, as is the case with the TIMESTAMP data type).
If you are converting values and want to bring all the time values to zero you can use the trunc function like this (which changes 12:07:00 to 00:00:00):
select trunc(to_date('2015/01/22 12:07:00','YYYY/MM/DD HH24:MI:SS'),'DD') as dt_with_time_zerod
from dual
Fiddle - http://sqlfiddle.com/#!4/6a3a6/2/0
If the source is itself a date and you want to convert the date to a string in the Oracle default date format ('DD-MON-RR') you can achieve that by running:
select to_char(trunc(to_date('2015/01/22 12:07:00','YYYY/MM/DD HH24:MI:SS'),'DD'),'DD-MON-RR') as dt_with_time_zerod
from dual
Fiddle - http://sqlfiddle.com/#!4/6a3a6/3/0
If it's a date field, to_char without a mask will give you what you say you want.
actually i want oracle standard date format without time stamp for this date '2015/01/22 00:00:00'
I'm not sure what you mean by "Oracle standard date format." The format in which a date would appear would be based on your NLS settings (in particular, NLS_DATE_FORMAT). If you are just trying to format this string representing a date, then you might want something like the following:
SELECT TO_CHAR(TO_DATE('2015/01/22 00:00:00','YYYY/MM/DD HH:MI:SS'), 'YYYY/MM/DD')
FROM dual;
That is, you have the TO_CHAR() and TO_DATE() functions in the wrong order, and an incomplete date mask for the call to TO_DATE().
Try using date literals with the standard ISO 8601 format.
date '2015-01-22'
I suggest you not to give hour-minute-second if you do not want to show the time.
This is my simplest answer :
SELECT TO_DATE('2015/01/22','YYYY/MM/DD') FROM dual

Convert string to date in Oracle SQL

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.