alter session set NLS_DATE_FORMAT='DD-MM-YYYY' : Session Variables « SQL PLUS Session Environment « Oracle PL/SQL Tutorial

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2. SQL PLUS Session Environment
3. Session Variables

SQL> create table history
  2  ( empno      NUMBER(4)
  3  , beginyear  NUMBER(4)
  4  , begindate  DATE
  5  , enddate    DATE
  6  , deptno     NUMBER(2)
  7  , sal       NUMBER(6,2)
  8  , comments   VARCHAR2(60)
  9  , constraint H_PK         primary key
 10                            (empno,begindate)
 11  , constraint H_BEG_END    check
 12                            (begindate < enddate)
 13  ) ;

Table created.

SQL>
SQL>
SQL> alter session  set NLS_DATE_FORMAT='DD-MM-YYYY';

Session altered.

SQL>
SQL> insert into history values (1,2000,'01-01-2000','01-02-2000',40, 950,'');

1 row created.

SQL> insert into history values (1,2000,'01-02-2000', NULL       ,20, 800,'restarted');

1 row created.

SQL>
SQL> insert into history values (2,1988,'01-06-1988','01-07-1989',30,1000,'');

1 row created.

SQL> insert into history values (2,1989,'01-07-1989','01-12-1993',30,1300,'');

1 row created.

SQL> insert into history values (2,1993,'01-12-1993','01-10-1995',30,1500,'');

1 row created.

SQL> insert into history values (2,1995,'01-10-1995','01-11-2009',30,1700,'');

1 row created.

SQL> insert into history values (2,2009,'01-11-2009', NULL       ,30,1600,'just hired');

1 row created.

SQL>
SQL>
SQL> select empno, begindate, comments
  2  from   history
  3  where  comments like '%0\%%' escape '\';

no rows selected

SQL>
SQL> drop table history;

Table dropped.

SQL>