Here is the table
SQL> SQL> drop table emp; Table dropped.-- from w w w . j a v a 2s . c o m SQL> create table emp( 2 empno NUMBER(4) primary key, 3 ename VARCHAR2(8) not null , 4 init VARCHAR2(5) not null , 5 job VARCHAR2(8) , 6 mgr NUMBER(4) , 7 bdate DATE not null , 8 msal NUMBER(6,2) not null , 9 comm NUMBER(6,2) , 10 deptno NUMBER(2) default 10) ; SQL> SQL> insert into emp values(7001,'SMITH','N', 'TRAINER', 7902,date '1975-12-17', 1800 , NULL, 20); SQL> insert into emp values(7002,'ALLEN','JAM','SALESREP',7006,date '1971-05-20', 1600, 300, 30); SQL> insert into emp values(7003,'WARD', 'TF' ,'SALESREP',7006,date '1972-03-02', 1250, 500, 10); SQL> insert into emp values(7004,'JACK', 'JM', 'MANAGER', 7009,date '1977-04-02', 2975, NULL, 20); SQL> insert into emp values(7005,'BROWN','P', 'SALESREP',7006,date '1976-09-28', 1250, 1400, 30); SQL> insert into emp values(7006,'BLAKE','R', 'MANAGER', 7009,date '1973-11-01', 2850, NULL, 10); SQL> insert into emp values(7007,'CLARK','AB', 'MANAGER', 7009,date '1975-06-09', 2450, NULL, 10); SQL> insert into emp values(7008,'SCOTT','DEF','TRAINER', 7004,date '1979-11-26', 3000, NULL, 20); SQL> insert into emp values(7009,'KING', 'CC', 'DIRECTOR',NULL,date '1972-10-17', 5000, NULL, 10); SQL> insert into emp values(7010,'BREAD','JJ', 'SALESREP',7006,date '1978-09-28', 1500, 0, 30); SQL> insert into emp values(7011,'ADAMS','AA', 'TRAINER', 7008,date '1976-12-30', 1100, NULL, 20); SQL> insert into emp values(7012,'JONES','R', 'ADMIN', 7006,date '1979-10-03', 8000, NULL, 30); SQL> insert into emp values(7902,'FORD', 'MG', 'TRAINER', 7004,date '1979-02-13', 3000, NULL, 20); SQL> insert into emp values(7934,'MARY', 'ABC','ADMIN', 7007,date '1972-01-23', 1300, NULL, 10); SQL> drop table offerings; Table dropped. SQL> create table offerings( 2 course VARCHAR2(6) not null, 3 begindate DATE not null, 4 trainer NUMBER(4) , 5 location VARCHAR2(8)) ; SQL> SQL> insert into offerings values ('SQL',date '1999-04-12',7902,'DALLAS' ); SQL> insert into offerings values ('JSON',date '1999-08-10',7004,'CHICAGO'); SQL> insert into offerings values ('SQL',date '1999-10-04',7001,'SEATTLE'); SQL> insert into offerings values ('SQL',date '1999-12-13',7001,'DALLAS' ); SQL> insert into offerings values ('JAVA',date '1999-12-13',7004,'SEATTLE'); SQL> insert into offerings values ('XML',date '2000-02-03',7001,'DALLAS' ); SQL> insert into offerings values ('JAVA',date '2000-02-01',7011,'DALLAS' ); SQL> insert into offerings values ('PLS',date '2000-09-11',7008,'DALLAS' ); SQL> insert into offerings values ('XML',date '2000-09-18',NULL,'SEATTLE'); SQL> insert into offerings values ('JSON',date '2000-09-27',7902,'DALLAS' ); SQL> insert into offerings values ('ERM',date '2001-01-15',NULL, NULL ); SQL> insert into offerings values ('PRO',date '2001-02-19',NULL,'DALLAS' ); SQL> insert into offerings values ('RSD',date '2001-02-24',7008,'CHICAGO'); SQL> SQL> drop table registrations; Table dropped. SQL> create table registrations( 2 attendee NUMBER(4) not null, 3 course VARCHAR2(6) , 4 begindate DATE not null, 5 evaluation NUMBER(1) check (evaluation in (1,2,3,4,5))) ; SQL> SQL> insert into registrations values (7002,'SQL',date '1999-04-12',4 ); SQL> insert into registrations values (7934,'SQL',date '1999-04-12',5 ); SQL> insert into registrations values (7006,'SQL',date '1999-04-12',4 ); SQL> insert into registrations values (7011,'SQL',date '1999-04-12',2 ); SQL> insert into registrations values (7008,'SQL',date '1999-10-04',NULL); SQL> insert into registrations values (7009,'SQL',date '1999-10-04',3 ); SQL> insert into registrations values (7902,'SQL',date '1999-10-04',4 ); SQL> insert into registrations values (7902,'SQL',date '1999-12-13',NULL); SQL> insert into registrations values (7006,'SQL',date '1999-12-13',NULL); SQL> insert into registrations values (7003,'JSON',date '1999-08-10',4 ); SQL> insert into registrations values (7012,'JSON',date '1999-08-10',4 ); SQL> insert into registrations values (7902,'JSON',date '1999-08-10',5 ); SQL> insert into registrations values (7010,'JSON',date '2000-09-27',5 ); SQL> insert into registrations values (7002,'JAVA',date '1999-12-13',2 ); SQL> insert into registrations values (7007,'JAVA',date '1999-12-13',NULL ); SQL> insert into registrations values (7011,'JAVA',date '1999-12-13',5 ); SQL> insert into registrations values (7008,'JAVA',date '1999-12-13',5 ); SQL> insert into registrations values (7009,'JAVA',date '1999-12-13',4 ); SQL> insert into registrations values (7004,'JAVA',date '2000-02-01',3 ); SQL> insert into registrations values (7008,'JAVA',date '2000-02-01',4 ); SQL> insert into registrations values (7006,'JAVA',date '2000-02-01',5 ); SQL> insert into registrations values (7012,'XML',date '2000-02-03',4 ); SQL> insert into registrations values (7002,'XML',date '2000-02-03',5 ); SQL> insert into registrations values (7004,'PLS',date '2000-09-11',NULL); SQL> insert into registrations values (7002,'PLS',date '2000-09-11',NULL); SQL> insert into registrations values (7011,'PLS',date '2000-09-11',NULL); SQL>
Write SQL to list names of all emp who ever attended an SQL course, with the name of the trainer.
SQL> SQL> select a.ename as attendee 2 , t.ename as trainer-- from w w w .j a va 2 s . co m 3 from emp t 4 join 5 offerings o on (o.trainer = t.empno) 6 join 7 registrations r using (course, begindate) 8 join 9 emp a on (r.attendee = a.empno) 10 where course = 'SQL'; ATTENDEE TRAINER -------- -------- ALLEN FORD MARY FORD BLAKE FORD ADAMS FORD SCOTT SMITH KING SMITH FORD SMITH FORD SMITH BLAKE SMITH 9 rows selected. SQL>