ORA-02449:
	unique/primary keys in table referenced by foreign keys
Cause: 	An attempt was made to drop a table with unique or primary keys referenced by foreign keys in another table.
Action: Before performing the above operations the table,
 drop the foreign key constraints in other tables. 
You can see what constraints are referencing a table by issuing the following command: 
SELECT * FROM USER_CONSTRAINTS WHERE TABLE_NAME = "tabnam";

SCOTT@orcl_11gR2> -- starting tables, data, and constraints:
SCOTT@orcl_11gR2> CREATE TABLE transaction_table
  2    (transaction_column  NUMBER,
  3  	CONSTRAINT transaction_pk PRIMARY KEY (transaction_column))
  4  /

Table created.

SCOTT@orcl_11gR2> INSERT INTO transaction_table (transaction_column)
  2  SELECT deptno FROM dept
  3  /

4 rows created.

SCOTT@orcl_11gR2> CREATE TABLE child_table
  2    (child_col	    NUMBER,
  3  	CONSTRAINT child_fk FOREIGN KEY (child_col)
  4  			    REFERENCES transaction_table (transaction_column))
  5  /

Table created.

SCOTT@orcl_11gR2> INSERT INTO child_table
  2  SELECT deptno FROM emp
  3  /

14 rows created.

SCOTT@orcl_11gR2> -- interim table:
SCOTT@orcl_11gR2> CREATE TABLE interim_table
  2    (transaction_column  NUMBER)
  3  PARTITION BY RANGE (transaction_column)
  4    (PARTITION part1 VALUES LESS THAN (21),
  5  	PARTITION partm VALUES LESS THAN (MAXVALUE))
  6  /

Table created.

SCOTT@orcl_11gR2> -- redefinition:
SCOTT@orcl_11gR2> DECLARE
  2    v_num_errors  NUMBER;
  3  BEGIN
  4    DBMS_REDEFINITION.CAN_REDEF_TABLE
  5  	 (USER,
  6  	  'TRANSACTION_TABLE');
  7    DBMS_REDEFINITION.START_REDEF_TABLE
  8  	 (USER,
  9  	  'TRANSACTION_TABLE',
 10  	  'INTERIM_TABLE');
 11    DBMS_REDEFINITION.COPY_TABLE_DEPENDENTS
 12  	 (USER,
 13  	  'TRANSACTION_TABLE',
 14  	  'INTERIM_TABLE',
 15  	  NUM_ERRORS => v_num_errors);
 16    DBMS_REDEFINITION.FINISH_REDEF_TABLE
 17  	 (USER,
 18  	  'TRANSACTION_TABLE',
 19  	  'INTERIM_TABLE');
 20    DBMS_OUTPUT.PUT_LINE ('errors:  ' || v_num_errors);
 21  END;
 22  /
errors:  0

PL/SQL procedure successfully completed.

SCOTT@orcl_11gR2> -- attempt to drop interim table fails without cascade constraints:
SCOTT@orcl_11gR2> DROP TABLE interim_table
  2  /
DROP TABLE interim_table
           *
ERROR at line 1:
ORA-02449: unique/primary keys in table referenced by foreign keys


SCOTT@orcl_11gR2> -- dropping interim table is successful with cascade constraints:
SCOTT@orcl_11gR2> DROP TABLE interim_table CASCADE CONSTRAINTS
  2  /

Table dropped.

SCOTT@orcl_11gR2> -- table is now partitioned:
SCOTT@orcl_11gR2> SELECT * FROM transaction_table PARTITION (part1)
  2  /

TRANSACTION_COLUMN
------------------
                10
                20

2 rows selected.

SCOTT@orcl_11gR2> SELECT * FROM transaction_table PARTITION (partm)
  2  /

TRANSACTION_COLUMN
------------------
                30
                40

2 rows selected.

SCOTT@orcl_11gR2> -- primary key constraint is still in effect:
SCOTT@orcl_11gR2> INSERT INTO transaction_table (transaction_column) VALUES (20)
  2  /
INSERT INTO transaction_table (transaction_column) VALUES (20)
*
ERROR at line 1:
ORA-00001: unique constraint (SCOTT.TRANSACTION_PK) violated


SCOTT@orcl_11gR2> -- foreign key on child table is still in effect:
SCOTT@orcl_11gR2> INSERT INTO child_table (child_col) VALUES (21)
  2  /
INSERT INTO child_table (child_col) VALUES (21)
*
ERROR at line 1:
ORA-02291: integrity constraint (SCOTT.CHILD_FK) violated - parent key not
found