Date type is unique by default?

Question

Hello,
I have created a table with date data type. All records are inserted but same date records throws following error:
ORA00001-unique constraint (aa.sys_C005487) violated
Best regards

Answer 1

Before you blindly drop the constraint, you might want to consider a few things.
Is there a real business reason why the constraint needs to be in place?
Is the constraint actually only on the single date column, or a combination of columns? You can use the user_cons_columns view to find out.
There will be a (probably) unique index supporting the constraint. You may want to consider if you need to keep it. If so, then, if it is a unique index, you will have to rebuild it after you drop the constraint. If the index is not unique then you can use the keep index clause on the drop constraint statement.
You should also make sure that ti is actually a constraint, and not just a unique index. For example:
SQL> CREATE TABLE t (id number, descr varchar2(10));
Table created.
SQL> CREATE UNIQUE INDEX t_unq ON t(id);
Index created.
SQL> INSERT INTO t VALUES (1, 'One');
1 row created.
SQL> INSERT INTO t VALUES (1, 'Ein');
INSERT INTO t VALUES (1, 'Ein')
ERROR at line 1:
ORA-00001: unique constraint (OPS$ORACLE.T_UNQ) violated
SQL> SELECT constraint_name, constraint_type
  2  FROM user_constraints
  3  WHERE table_name = 'T';
no rows selectedJohn