SQL>
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 (empno,begindate)
10 , constraint H_BEG_END check (begindate < enddate)
11 ) ;
Table created.
SQL>
SQL>
SQL> alter session set NLS_DATE_FORMAT='DD-MM-YYYY';
Session altered.
SQL>
SQL> insert into history values (1,2000,'01-02-2000', NULL ,20, 800,'restarted');
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> insert into history values (3,1986,'01-10-1986','01-08-1987',20,1000,'');
1 row created.
SQL> insert into history values (3,1987,'01-08-1987','01-01-1989',30,1000,'On training');
1 row created.
SQL> insert into history values (3,2000,'01-02-2000', NULL ,30,1250,'');
1 row created.
SQL>
SQL> select *
2 from (select empno, sal
3 from history
4 order by sal desc)
5 where rownum <= 3;
EMPNO SAL
---------- ----------
2 1700
2 1600
3 1250
SQL>
SQL> drop table history;
Table dropped.
SQL>
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