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SQL>
SQL>
SQL>
SQL> create table course_schedule
2 ( course VARCHAR2(6)
3 , begindate DATE
4 , trainer NUMBER(4)
5 , location VARCHAR2(20)) ;
Table created.
SQL>
SQL>
SQL> insert into course_schedule values ('SQL',date '1999-04-12',1,'VANCOUVER' );
1 row created.
SQL> insert into course_schedule values ('OAU',date '1999-08-10',2,'CHICAGO');
1 row created.
SQL> insert into course_schedule values ('SQL',date '1999-10-04',3,'SEATTLE');
1 row created.
SQL> insert into course_schedule values ('SQL',date '1999-12-13',4,'DALLAS' );
1 row created.
SQL> insert into course_schedule values ('JAV',date '1999-12-13',5,'SEATTLE');
1 row created.
SQL> insert into course_schedule values ('XML',date '2000-02-03',6,'VANCOUVER' );
1 row created.
SQL> insert into course_schedule values ('JAV',date '2000-02-01',7,'DALLAS' );
1 row created.
SQL> insert into course_schedule values ('PLS',date '2000-09-11',8,'VANCOUVER' );
1 row created.
SQL> insert into course_schedule values ('XML',date '2000-09-18',NULL,'SEATTLE');
1 row created.
SQL> insert into course_schedule values ('OAU',date '2000-09-27',9,'DALLAS' );
1 row created.
SQL> insert into course_schedule values ('ERM',date '2001-01-15',10, NULL );
1 row created.
SQL> insert into course_schedule values ('PRO',date '2001-02-19',NULL,'VANCOUVER' );
1 row created.
SQL> insert into course_schedule values ('RSD',date '2001-02-24',8,'CHICAGO');
1 row created.
SQL>
SQL>
SQL> create table registrations
2 ( attendee NUMBER(4)
3 , course VARCHAR2(6)
4 , begindate DATE
5 , evaluation NUMBER(1)) ;
Table created.
SQL>
SQL>
SQL> insert into registrations values (1, 'SQL',date '1999-04-12',4 );
1 row created.
SQL> insert into registrations values (2, 'SQL',date '1999-12-13',NULL);
1 row created.
SQL> insert into registrations values (3, 'SQL',date '1999-12-13',NULL);
1 row created.
SQL> insert into registrations values (4, 'OAU',date '1999-08-10',4 );
1 row created.
SQL> insert into registrations values (5, 'OAU',date '2000-09-27',5 );
1 row created.
SQL> insert into registrations values (6, 'JAV',date '1999-12-13',2 );
1 row created.
SQL> insert into registrations values (7, 'JAV',date '2000-02-01',4 );
1 row created.
SQL> insert into registrations values (8, 'JAV',date '2000-02-01',5 );
1 row created.
SQL> insert into registrations values (9, 'XML',date '2000-02-03',4 );
1 row created.
SQL> insert into registrations values (10,'XML',date '2000-02-03',5 );
1 row created.
SQL> insert into registrations values (1, '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 (3, 'PLS',date '2000-09-11',NULL);
1 row created.
SQL>
SQL>
SQL>
SQL> select o.trainer, avg(r.evaluation)
2 from course_schedule o
3 join
4 registrations r
5 using (course,begindate)
6 group by o.trainer;
TRAINER AVG(R.EVALUATION)
---------- -----------------
1 4
6 4.5
2 4
4
5 2
8
7 4.5
9 5
8 rows selected.
SQL>
SQL> drop table course_schedule;
Table dropped.
SQL>
SQL> drop table registrations;
Table dropped.
SQL>
SQL>
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