SQL>
SQL> create table courses
2 ( code VARCHAR2(6) constraint C_PK
3 primary key
4 , description VARCHAR2(30)
5 , category CHAR(3)
6 , duration NUMBER(2)
7 ) ;
Table created.
SQL> insert into courses values('SQL','SQL','GEN',4);
1 row created.
SQL> insert into courses values('OAU','Java','GEN',1);
1 row created.
SQL> insert into courses values('JAV','C++','BLD',4);
1 row created.
SQL> insert into courses values('PLS','C','BLD',1);
1 row created.
SQL> insert into courses values('XML','XML','BLD',2);
1 row created.
SQL> insert into courses values('ERM','ERP','DSG',3);
1 row created.
SQL> insert into courses values('PMT','ERP','DSG',1);
1 row created.
SQL> insert into courses values('RSD','jQuery','DSG',2);
1 row created.
SQL> insert into courses values('PRO','Linux','DSG',5);
1 row created.
SQL> insert into courses values('GEN','Oracle','DSG',4);
1 row created.
SQL>
SQL> select code, category, duration
2 from courses
3 where (category = 'BLD' or duration = 2)
4 and not (category = 'BLD' and duration = 2);
CODE CAT DURATION
------ --- ----------
JAV BLD 4
PLS BLD 1
RSD DSG 2
SQL>
SQL>
SQL> drop table courses;
Table dropped.