Not Null Constraint In SQL

 Not Null Constraint:

====================

  -Restricted nulls but accepting duplicates

  

  -Not null an not be applied at table level

ex::

create table test1(eid int not null,ename varchar2(10) not null);

EX::

SQL> create table test1(eid int not null,ename varchar2(10) not null);

Table created.

SQL> insert into test1 values(10,'raja');

1 row created.

SQL> insert into test1 values(20,'dan');

1 row created.

SQL> select * from test1;

       EID ENAME

---------- ----------

        10 raja

        20 dan

SQL> insert into test1 values(null,'dan');

insert into test1 values(null,'dan')

                         *

ERROR at line 1:

ORA-01400: cannot insert NULL into ("SYSTEM"."TEST1"."EID")

SQL> insert into test1 values(10,null);

insert into test1 values(10,null)

                            *

ERROR at line 1:

ORA-01400: cannot insert NULL into ("SYSTEM"."TEST1"."ENAME")

SQL> select * from test1;

       EID ENAME

---------- ----------

        10 raja

        20 dan

SQL> insert into test1 values(10,'raja');

1 row created.

SQL> select * from test1;

       EID ENAME

---------- ----------

        10 raja

        20 dan

        10 raja

SQL> insert into test1 values(20,'randy');

1 row created.

SQL> select * from test1;

       EID ENAME

---------- ----------

        10 raja

        20 dan

        10 raja

        20 randy

SQL> create table test2(eid int,ename varchar2(10),not null(eid,ename));

create table test2(eid int,ename varchar2(10),not null(eid,ename))

                                              *

ERROR at line 1:

ORA-00904: : invalid identifier