Answer Posted / sabariesh thavamani

i worked out the coding in the above using oracle 9 i, but
i could not get the correct answer what he told.. try it

SQL> create table sab(name varchar2(10) unique);

Table created.

SQL> insert into sab values('&sab');
Enter value for sab: null
old 1: insert into sab values('&sab')
new 1: insert into sab values('null')

1 row created.

SQL> /
Enter value for sab: null
old 1: insert into sab values('&sab')
new 1: insert into sab values('null')
insert into sab values('null')
*
ERROR at line 1:
ORA-00001: unique constraint (LPUSER18.SYS_C0038068)
violated


SQL> /
Enter value for sab: sabari
old 1: insert into sab values('&sab')
new 1: insert into sab values('sabari')

1 row created.

SQL> /
Enter value for sab: null
old 1: insert into sab values('&sab')
new 1: insert into sab values('null')
insert into sab values('null')
*
ERROR at line 1:
ORA-00001: unique constraint (LPUSER18.SYS_C0038068)
violated


SQL> select * from sab
2 ;

NAME
----------
null
sabari
try it....

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