SQL TO_DATE - for every single date field? - sql

Question

After years of using MySQL, having to move a table over to Oracle SQL (am using SQL Developer). Created the table and now just wanted to check it with a single INSERT statement, getting this:
INSERT INTO table_name
VALUES ('1001','LAWRENCE-INDIANAPOLIS','01-06-02','I8112NP','05DX8105408','2013-06-03','2016-03-11','2018-04-29','2038-01-01','yes','yes','yes','2012-10-25','CCE','7360D33','R8NR6N0','70F63951959F9','2016-03-11')
Error report -
SQL Error: ORA-01861: literal does not match format string
01861. 00000 - "literal does not match format string"
*Cause: Literals in the input must be the same length as literals in
the format string (with the exception of leading whitespace).
If the "FX" modifier has been toggled on, the literal must match exactly,
with no extra whitespace.
*Action: Correct the format string to match the literal.
Do I really have to put a TO_DATE format in front of every single DATE field in the INSERT statement, even though they're already in the proper YYYY-MM-DD format?

Answer 1

Well, you don't have to do it every time, but good practice says that you should instruct Oracle what you have and what you expect of it to do.
It is about NLS settings. If date format is different from one you use, you'll get an error (as you already know it):
SQL> create table test (datum date);
Table created.
SQL> insert into test values ('2013-06-03');
insert into test values ('2013-06-03')
*
ERROR at line 1:
ORA-01861: literal does not match format string
But, if you modify date format so that it matches format you use, everything will be OK:
SQL> alter session set nls_date_format = 'yyyy-mm-dd';
Session altered.
SQL> insert into test values ('2013-06-03');
1 row created.
SQL>
Another option, which doesn't depend on NLS settings, is to use DATE literal. It is always in format YYYY-MM-DD and has to be preceded by the DATE keyword:
SQL> alter session set nls_date_format = 'dd.mm.yyyy';
Session altered.
SQL> insert into test values ('2013-06-03');
insert into test values ('2013-06-03')
*
ERROR at line 1:
ORA-01861: literal does not match format string
SQL> insert into test values (date '2013-06-03');
1 row created.
SQL>
Or, as you found out, use TO_DATE function with the appropriate format mask.

Answer 2

In Oracle, use the date keyword:
INSERT INTO table_name
VALUES ('1001', 'LAWRENCE-INDIANAPOLIS', '01-06-02', 'I8112NP', '05DX8105408',
DATE '2013-06-03', DATE '2016-03-11', DATE '2018-04-29', DATE '2038-01-01', 'yes', 'yes', 'yes', DATE '2012-10-25', 'CCE', '7360D33', 'R8NR6N0', '70F63951959F9', DATE '2016-03-11'
);

Answer 3

The default DATE format used depends on the setting of the NLS_DATE_FORMAT environment var. To find out what this is, use the following query:
SELECT *
FROM V$NLS_PARAMETERS
ORDER BY PARAMETER;
This will dump all of the NLS parameters as they are currently set in your database. As an example, in the database I'm working in right now the query above returns:
NLS_CALENDAR GREGORIAN
NLS_CHARACTERSET US7ASCII
NLS_COMP BINARY
NLS_CURRENCY $
NLS_DATE_FORMAT DD-MON-RR
NLS_DATE_LANGUAGE AMERICAN
NLS_DUAL_CURRENCY $
NLS_ISO_CURRENCY AMERICA
NLS_LANGUAGE AMERICAN
NLS_LENGTH_SEMANTICS BYTE
NLS_NCHAR_CHARACTERSET AL16UTF16
NLS_NCHAR_CONV_EXCP FALSE
NLS_NUMERIC_CHARACTERS .,
NLS_SORT BINARY
NLS_TERRITORY AMERICA
NLS_TIMESTAMP_FORMAT DD-MON-RR HH.MI.SSXFF AM
NLS_TIMESTAMP_TZ_FORMAT DD-MON-RR HH.MI.SSXFF AM TZR
NLS_TIME_FORMAT HH.MI.SSXFF AM
NLS_TIME_TZ_FORMAT HH.MI.SSXFF AM TZR
So on my system, if I wanted to enter a date-as-character string and have Oracle translate it correctly I'd have to enter is as e.g. 24-Apr-18.