Howto check all tables if have unique key

Question

I need to check all tables if they have unique key. If they do not i must print it.
How can i make this in PL/SQL
regards

Answer 1

But dba_constraints is not storing the information when i establish a unique constraint by creating unique index.
SQL> create table t as select level no from dual connect by level <= 10
  2  /
Table created.
SQL> create unique index t_idx on t(no)
  2  /
Index created.
SQL> select distinct table_name
  2    from user_indexes
  3   where uniqueness = 'UNIQUE'
  4     and table_name = 'T'
  5  /
TABLE_NAME
T
SQL> select * from dba_constraints where constraint_type = 'U' and table_name = 'T'
  2  /
no rows selected
SQL> select * from dba_constraints where table_name = 'T'
  2  /
no rows selected
SQL> select * from user_constraints where table_name = 'T'
  2  /
no rows selected
SQL>But on the other hand user_indexes has it in all case
SQL> drop table t
  2  /
Table dropped.
SQL> create table t(no number unique)
  2  /
Table created.
SQL> select distinct table_name
  2    from user_indexes
  3   where uniqueness = 'UNIQUE'
  4     and table_name = 'T'
  5  /
TABLE_NAME
T
SQL> select * from dba_constraints where table_name = 'T'
  2  /
OWNER                          CONSTRAINT_NAME                C TABLE_NAME                     SEARCH_CONDITION
                        R_OWNER                        R_CONSTRAINT_NAME              DELETE_RU
STATUS   DEFERRABLE     DEFERRED  VALIDATED     GENERATED      BAD RELY LAST_CHAN INDEX_OWNER            INDEX_NAME                     INVALID VIEW_R
ELATED
SYSADM                         SYS_C00391103                  U T
ENABLED  NOT DEFERRABLE IMMEDIATE VALIDATED     GENERATED NAME          02-SEP-08 SYSADM                 SYS_C00391103Thanks,
Karthick.