I have a question about selecting year from a date. This is in Oracle database 12c.
Given that SELECT trunc(SYSDATE) FROM DUAL;
returns 02/06/2020
These work proper and return current year of 2020
-
SELECT EXTRACT(YEAR FROM trunc(SYSDATE)) FROM DUAL;
SELECT TO_CHAR(trunc(SYSDATE,'YYYY')) FROM DUAL;
These do not work and give error -
SELECT EXTRACT(YEAR FROM '02/06/2019') FROM DUAL;
Gives error: ORA-30076: invalid extract field for extract source
SELECT TO_CHAR('02/06/2019','YYYY') FROM DUAL;
Gives error: ORA-01722: invalid number
The same format is being passed with sysdate and hard coded date of 02/06/2019. Why is it that one works and the other does not?
I know I could just select 2019 from dual
but that is not the point or use case here.
You can't extract year from a string (which '02/06/2019'
is). First convert it to date:
SQL> SELECT EXTRACT(YEAR FROM to_date('02/06/2019', 'dd/mm/yyyy')) year FROM DUAL;
YEAR
----------
2019
SQL>
Or, if you know that last 4 digits are valid year, then
SQL> select substr('02/06/2019', -4) year from dual;
YEAR
----
2019
SQL>
It comes down to the data type being passed. sysdate
by default is a DATE field. A hard date like '02/06/2020' by default is considered a string.
To get around that, just cast the string as a date. All good.
SELECT TO_CHAR(cast('6-feb-2019' as date),'YYYY') FROM DUAL;
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