how to know the constraints on table in oracle..............

select * from user_cons_columns ucc, user_constraints uc 

where uc.constraint_name=ucc.constraint_name

and uc.constraint_type='P' and uc.table_name = 'Table Name';

R = Referential Constraint/Foreign Key constraint

C = Check Constraint

P = Primary Key

U = Unique Key

(or)

select 

   cons.owner            as child_owner, 

   cons.table_name       as child_table,

   cons.constraint_name     constaint_name,

   cons.constraint_type     constraint_type,

   col.owner                parent_owner, 

   col.table_name           parent_table,

   col.column_name          column_name

from dba_cons_columns      col, 

     dba_constraints       cons

where 

   cons.r_owner = col.owner

and 

   cons.r_constraint_name = col.constraint_name

and 

   cons.table_name = 'Table Name';

   

(or)

   select * 

from

    all_constraints 

where

    r_constraint_name in

    (select       constraint_name

    from

       all_constraints

    where

       table_name='Table Name')