create unique index with case ... when statement : Create Index « Index « Oracle PL / SQL






  1. Oracle PL / SQL
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create unique index with case ... when statement

    
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 (8,'JAV',date '2009-12-13',5   );

1 row created.

SQL> insert into registrations values (9,'JAV',date '2009-12-13',4   );

1 row created.

SQL> insert into registrations values (4,'JAV',date '2000-02-01',3   );

1 row created.

SQL> insert into registrations values (8,'JAV',date '2000-02-01',4   );

1 row created.

SQL> insert into registrations values (6,'JAV',date '2000-02-01',5   );

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> create unique index oau_reg on registrations
  2  ( case course when 'OAU' then attendee else null end
  3  , case course when 'OAU' then course   else null end );

Index created.

SQL>
SQL> insert into registrations values (12,'OAU',sysdate,null);

1 row created.

SQL>
SQL> drop index oau_reg;

Index dropped.

SQL> drop table registrations;

Table dropped.








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