SQL> desc dept
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 DEPTNO                                    NOT NULL NUMBER(2)
 DNAME                                     NOT NULL VARCHAR2(14)
 LOC                                                VARCHAR2(13)

SQL> get 1
  1  select a.table_name,b.column_name,a.constraint_name,a.constraint_type from
  2  user_constraints a,user_cons_columns b
  3  where a.constraint_name=b.constraint_name and
  4* b.table_name='DEPT'
SQL> /

TABLE_NAME COLUMN_NAME          CONSTRAINT_NAME                C
---------- -------------------- ------------------------------ -
DEPT       DEPTNO               SYS_C003283                    P
DEPT       DNAME                SYS_C003282                    C