Column format: default value for null value : Null Value Concatanation « Select Query « Oracle PL / SQL






  1. Oracle PL / SQL
  2. Select Query
  3. Null Value Concatanation

Column format: default value for null 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> column evaluation NULL "unknown!!!"
SQL>
SQL> select * from registrations
  2  where  attendee = 4;

no rows selected

SQL>
SQL>
SQL> drop table registrations;

Table dropped.








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