NOT NULL Column Constraints : NOT NULL « Constraints « Oracle PL / SQL

1. Oracle PL / SQL
2. Constraints
3. NOT NULL

NOT NULL Column Constraints

   
SQL>
SQL> create table people(
  2    employee_id     number(9),
  3    first_name      varchar2(15),
  4    last_name       varchar2(20),
  5    email           varchar2(25),
  6    constraint pk_people primary key (employee_id)
  7  );

Table created.

SQL>
SQL> insert into people values (1, 'T', 'Kyte', 'YourName@q.com');

1 row created.

SQL>
SQL> insert into people values (2, 'S', 'Viper', 'sdillon@q.com');

1 row created.

SQL>
SQL> insert into people values (3, 'C', 'Beck', 'clbeck@q.com');

1 row created.

SQL>
SQL> commit;

Commit complete.

SQL>
SQL> select * from people;

EMPLOYEE_ID FIRST_NAME      LAST_NAME            EMAIL
----------- --------------- -------------------- -------------------------
          1 T               Kyte                 YourName@q.com
          2 S               Viper                sdillon@q.com
          3 C               Beck                 clbeck@q.com

SQL>
SQL>
SQL> alter table people
  2  add (
  3    ssn       number(9)
  4  );

Table altered.

SQL>
SQL> update people set ssn = 123456789 where employee_id = 1;

1 row updated.

SQL>
SQL> update people set ssn = 234567890 where employee_id = 2;

1 row updated.

SQL>
SQL> update people set ssn = 345678901 where employee_id = 3;

1 row updated.

SQL>
SQL> alter table people
  2  modify (
  3    ssn number(9) not null
  4  );

Table altered.

SQL>
SQL> desc people;
 Name                                                                                                      Null?    Type
 ----------------------------------------------------------------------------------------------------------------- -------- ----------------------------------------------------------------------------
 EMPLOYEE_ID                                                                                               NOT NULL NUMBER(9)
 FIRST_NAME                                                                                                         VARCHAR2(15)
 LAST_NAME                                                                                                          VARCHAR2(20)
 EMAIL                                                                                                              VARCHAR2(25)
 SSN                                                                                                       NOT NULL NUMBER(9)

SQL>
SQL> drop table people;

Table dropped.

SQL>
SQL>

   
    
  

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