Use case when clause to decode value

   

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 (6,'SQL',date '2009-12-13',NULL);

1 row created.

SQL> insert into registrations values (3,'OAU',date '2009-08-10',4   );

1 row created.

SQL> insert into registrations values (12,'OAU',date '2009-08-10',4   );

1 row created.

SQL> insert into registrations values (13,'OAU',date '2009-08-10',5   );

1 row created.

SQL>
SQL> select attendee, begindate
  2  ,      case evaluation
  3              when 1 then 'bad'
  4              when 2 then 'mediocre'
  5              when 3 then 'ok'
  6              when 4 then 'good'
  7              when 5 then 'excellent'
  8                     else 'not filled in'
  9         end
 10  from   registrations
 11  where  course = 'SQL';

  ATTENDEE BEGINDATE  CASEEVALUATIO
---------- ---------- -------------
         2 12-04-2009 good
        14 12-04-2009 excellent
         6 12-04-2009 good
        11 12-04-2009 mediocre
         8 04-10-2009 not filled in
         9 04-10-2009 ok
        13 04-10-2009 good
        13 13-12-2009 not filled in
         6 13-12-2009 not filled in

9 rows selected.

SQL>
SQL>
SQL> drop table registrations;

Table dropped.

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Use case when clause to decode value : Case Query « Select Query « Oracle PL / SQL

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