SQL> --Constraint types
SQL> --There are five integrity constraints in Oracle.
SQL> --Not Null
SQL>
SQL> create table myTable (
2 a number not null,
3 b number null,
4 c number
5 );
Table created.
SQL>
SQL> insert into myTable values ( 1, null, null);
1 row created.
SQL> insert into myTable values ( 2, 3, 4);
1 row created.
SQL> insert into myTable values (null, 5, 6);
insert into myTable values (null, 5, 6)
*
ERROR at line 1:
ORA-01400: cannot insert NULL into ("SYS"."MYTABLE"."A")
SQL>
SQL> drop table myTable;
Table dropped.
SQL>