SQL>create table ttt (a number not null);
Table created.
SQL> select * from user_constraints
2where TABLE_NAME='TTT';
OWNER
CONSTRAINT_NAME
C TABLE_NAME
SEARCH_CONDITION
------------------------------ ------------------------------ - ------------------------------ -------------------------------------------
SYS
SYS_C005540
C TTT
"A" IS NOT NULL
SQL> insert into ttt values(1);
1 row created.
SQL>insert into ttt values(null);
insert into ttt values(null)
*
ERROR at line 1:
ORA-01400: cannot insert NULL into ("SYS"."TTT"."A"
SQL> alter table ttt disable constraint SYS_C005540;
Table altered.
SQL> insert into ttt values(null);
1 row created.
SQL> select * from ttt;
A
----------
1
