Oracle SQL - Write SQL to list course code offerings with at least three registrations.

Requirements

Here is the table

Demo

SQL>
SQL> drop table registrations;

Table dropped.--   w w w .j  a v  a 2 s . com

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 the course code, begin date, and the number of registrations for all course offerings in 1999 with at least three registrations.

Demo

SQL>
SQL> select   course
  2  ,        begindate--   w  ww .j av a2  s.c o  m
  3  ,        count(*)
  4  from     registrations
  5  where    extract(year from begindate) = 1999
  6  group by course
  7  ,        begindate
  8  having   count(*) >= 3;

COURSE BEGINDATE   COUNT(*)
------ --------- ----------
JAVA   13-DEC-99          5
JSON   10-AUG-99          3
SQL    12-APR-99          4
SQL    04-OCT-99          3

SQL>

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