FUNCTION IN UNIQUE KEY

Question

Hi,
We have a timestamp column.
We must put a unique key on it but without the milliseconds
Is it possible to create a unique key with a function inside ?
The function will return the date without milliseconds ?
We see it's possible to create unique index with function but we didn't find example with unique key.
Thanks
Alexandre

Answer 1

Hmmm, a nice suggestion Laurent but it's not quite right on my 9.2 db...
SQL> create table t02 as select current_timestamp t from dual;
Table created.
SQL> create unique index i02 on t02(cast(t as date));
Index created.
SQL> insert into  t02  select current_timestamp t from dual;
1 row created.
SQL> r
  1* insert into  t02  select current_timestamp t from dual
1 row created.
SQL> r
  1* insert into  t02  select current_timestamp t from dual
1 row created.
SQL> r
  1* insert into  t02  select current_timestamp t from dual
insert into  t02  select current_timestamp t from dual
ERROR at line 1:
ORA-00001: unique constraint (APC.I02) violated
SQL> r
  1* insert into  t02  select current_timestamp t from dual
1 row created.
SQL> r
  1* insert into  t02  select current_timestamp t from dual
1 row created.
SQL> r
  1* insert into  t02  select current_timestamp t from dual
insert into  t02  select current_timestamp t from dual
ERROR at line 1:
ORA-00001: unique constraint (APC.I02) violated
SQL> SELECT to_char(t, 'DD-MON-YYYY HH24:MI:SS') FROM t02;
TO_CHAR(T,'DD-MON-YY
02-DEC-2005 09:55:11
02-DEC-2005 09:55:46
02-DEC-2005 09:55:48
02-DEC-2005 09:55:48
02-DEC-2005 09:55:54
02-DEC-2005 09:55:55
6 rows selected.
SQL> Cheers, APC