|
SQL> create table offerings
2 ( course VARCHAR2(6)
3 , begindate DATE
4 , trainer NUMBER(4)
5 , location VARCHAR2(8)
6 ) ;
Table created.
SQL> insert into offerings values ('SQL',date '2009-04-12',13,'DALLAS' );
1 row created.
SQL> insert into offerings values ('OAU',date '2009-08-10',4,'CHICAGO');
1 row created.
SQL> insert into offerings values ('SQL',date '2009-10-04',1,'SEATTLE');
1 row created.
SQL> insert into offerings values ('SQL',date '2009-12-13',1,'DALLAS' );
1 row created.
SQL> insert into offerings values ('JAV',date '2009-12-13',4,'SEATTLE');
1 row created.
SQL> insert into offerings values ('XML',date '2000-02-03',1,'DALLAS' );
1 row created.
SQL> insert into offerings values ('JAV',date '2000-02-01',11,'DALLAS' );
1 row created.
SQL> insert into offerings values ('PLS',date '2000-09-11',8,'DALLAS' );
1 row created.
SQL> insert into offerings values ('XML',date '2000-09-18',NULL,'SEATTLE');
1 row created.
SQL> insert into offerings values ('OAU',date '2000-09-27',13,'DALLAS' );
1 row created.
SQL> insert into offerings values ('ERM',date '2001-01-15',NULL, NULL );
1 row created.
SQL> insert into offerings values ('PRO',date '2001-02-19',NULL,'DALLAS' );
1 row created.
SQL> insert into offerings values ('RSD',date '2001-02-24',8,'CHICAGO');
1 row created.
SQL>
SQL> create table registrations
2 ( attendee NUMBER(4)
3 , course VARCHAR2(6)
4 , begindate DATE
5 , evaluation NUMBER(1)
6 , constraint R_PK primary key(attendee,course,begindate)
7 ) ;
Table created.
SQL>
SQL> insert into registrations values (2,'SQL',date '2009-04-12',4 );
1 row created.
SQL> insert into registrations values (14,'SQL',date '2009-04-12',5 );
1 row created.
SQL> insert into registrations values (6,'SQL',date '2009-04-12',4 );
1 row created.
SQL> insert into registrations values (11,'SQL',date '2009-04-12',2 );
1 row created.
SQL> insert into registrations values (8,'SQL',date '2009-10-04',NULL);
1 row created.
SQL> insert into registrations values (9,'SQL',date '2009-10-04',3 );
1 row created.
SQL> insert into registrations values (13,'SQL',date '2009-10-04',4 );
1 row created.
SQL> insert into registrations values (13,'SQL',date '2009-12-13',NULL);
1 row created.
SQL> insert into registrations values (12,'XML',date '2000-02-03',4 );
1 row created.
SQL> insert into registrations values (2,'XML',date '2000-02-03',5 );
1 row created.
SQL> insert into registrations values (4,'PLS',date '2000-09-11',NULL);
1 row created.
SQL> insert into registrations values (2,'PLS',date '2000-09-11',NULL);
1 row created.
SQL> insert into registrations values (11,'PLS',date '2000-09-11',NULL);
1 row created.
SQL>
SQL>
SQL> select o.trainer, avg(r.evaluation)
2 from offerings o
3 join
4 registrations r
5 using (course,begindate)
6 group by o.trainer;
TRAINER AVG(R.EVALUATION)
---------- -----------------
1 4
8
13 3.75
SQL>
SQL> drop table registrations;
Table dropped.
SQL>
SQL> drop table offerings;
Table dropped.
|