TO_DATE ISSUE IN CONVERSION - oracle

Question

I tried to execute the below query but it's throwing me error :
SELECT TO_DATE(
TIMESTAMP '1970-01-01 00:00:00' + numtodsinterval(1511421211, 'second')
,'DD-MM-YYYY HH24:MI:SS')
FROM dual
Error : ORA-01830: date format picture ends before converting entire input string

Answer 1

The TO_DATE( datestring, format_model ) function takes strings as arguments.
Your query:
SELECT TO_DATE(
TIMESTAMP '1970-01-01 00:00:00' + numtodsinterval(1511421211, 'second')
,'DD-MM-YYYY HH24:MI:SS'
)
FROM dual
Is passing a TIMESTAMP and a string so Oracle has to perform an implicit conversion from TIMESTAMP to a string so your function is effectively:
SELECT TO_DATE(
TO_CHAR(
TIMESTAMP '1970-01-01 00:00:00' + numtodsinterval(1511421211, 'second'),
(
SELECT value
FROM NLS_SESSION_PARAMETERS
WHERE parameter = 'NLS_TIMESTAMP_FORMAT'
)
),
'DD-MM-YYYY HH24:MI:SS'
)
FROM dual
If the NLS_TIMESTAMP_FORMAT session paramter does not match your format model 'DD-MM-YYYY HH24:MI:SS' then an exception will be raised.
You could change the NLS_TIMESTAMP_FORMAT parameter - but this is a session parameter that is set per user and each user can change it at any time during their session so this should NOT be the solution.
Instead, you can just use a DATE literal instead of a TIMESTAMP literal:
SELECT DATE '1970-01-01' + NUMTODSINTERVAL (1511421211, 'second')
FROM DUAL
Or, if you want to use a timestamp then you can use the CAST function:
SELECT CAST(
TIMESTAMP '1970-01-01 00:00:00' + NUMTODSINTERVAL (1511421211, 'second')
AS DATE
)
FROM DUAL

Answer 2

Is this what you are expecting?
select to_char(DATE '1970-01-01' + NUMTODSINTERVAL (1511421211, 'second'), 'yyyy/mm/dd hh24:mi:ss') from dual;

Answer 3

The syntax appear somewhat incorrect to me. Try this:
SELECT TO_DATE ('1970-01-01 00:00:00', 'YYYY-MM-DD HH24:MI:SS')
+ NUMTODSINTERVAL (1511421211, 'second')
FROM DUAL;
Edit:
As #a_horse.. said "Oracle DATE always contains a time",so if timestamp is not visible then you just need to see your NLS_DATE_FORMAT in table V$NLS_PARAMETERS. In your case its simply set to
NLS_DATE_FORMAT = 'DD-MM-YYYY';
So you need to alter the session first to get the timestamp in SQLPLUS. See below:
SQL> alter session set NLS_DATE_FORMAT = 'mm-dd-yyyy HH24:mi:ss';
Session altered.
SQL> SELECT TO_DATE ('1970-01-01 00:00:00', 'YYYY-MM-DD HH24:MI:SS') + NUMTODSINTERVAL (15114212
11, 'second') FROM DUAL;
TO_DATE('1970-01-01
-------------------
11-23-2017 07:13:31