Oracle 21c

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ALTER SESSION SET NLS_DATE_FORMAT = 'dd-mm-rr';
select *
from nls_session_parameters
where parameter = 'NLS_DATE_FORMAT';

PARAMETER
VALUE

NLS_DATE_FORMAT
dd-mm-rr

select * from V$VERSION;

BANNER
BANNER_FULL
BANNER_LEGACY
CON_ID

Oracle Database 21c Express Edition Release 21.0.0.0.0 - Production
Oracle Database 21c Express Edition Release 21.0.0.0.0 - Production
Version 21.3.0.0.0
Oracle Database 21c Express Edition Release 21.0.0.0.0 - Production
0

create table CUST_TRANS (
  CUSTNO char(2) not null
 ,TRANSDATE date
 ,TRANSAMT number(6,2)
)
insert into CUST_TRANS values ('11', '01-JAN-07', 1000)
1 rows affected

insert into CUST_TRANS values ('22', '01-FEB-07', 2000)
1 rows affected

insert into CUST_TRANS values ('33', '01-MAR-07', 3000)
1 rows affected

SELECT transdate + '10' FROM cust_trans;

TRANSDATE+'10'

11-01-07

11-02-07

11-03-07

SELECT * FROM cust_trans WHERE transdate = '01-01-07';

CUSTNO
TRANSDATE
TRANSAMT

11
01-01-07
1000

SELECT transamt FROM cust_trans WHERE custno > '11';
    
TRANSAMT

2000

3000

SELECT * FROM cust_trans WHERE transdate='01-JANUARY-07';

CUSTNO
TRANSDATE
TRANSAMT

11
01-01-07
1000

SELECT custno + 'A' FROM cust_trans WHERE transamt > 2000;
ORA-01722: invalid number

ALTER SESSION SET NLS_DATE_FORMAT = 'DD MON YYYY';
SELECT * FROM cust_trans WHERE transdate = '01-01-07';
ORA-01843: not a valid month