Column name alias for count function : Alias « Query Select « Oracle PL/SQL Tutorial

1. Oracle PL/SQL Tutorial
2. Query Select
3. Alias

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 r.course, r.begindate
  2  ,      count(r.attendee) as attendees
  3  from   registrations r
  4  group  by r.course, r.begindate;

COURSE BEGINDATE  ATTENDEES
------ --------- ----------
OAU    27-SEP-00          1
PLS    11-SEP-00          3
SQL    12-APR-99          1
JAV    13-DEC-99          1
SQL    13-DEC-99          2
JAV    01-FEB-00          2
XML    03-FEB-00          2
OAU    10-AUG-99          1

8 rows selected.

SQL>
SQL>
SQL> drop table registrations;

Table dropped.

SQL>