Truncate a parent table

I overlooked the operations required to truncate a parent table. I thought I only need to
truncate all of its child tables first, then truncate itself. The following test demonstrated
that constraints have to be taken care of in addition:


SQL> @fk_child
Enter value for 1: z9xxx94
Enter value for 2: p
----- Children of z9xxx94 p -------

Owner Table Name Constraint Name Ref Constraint Name Status
-------------- ----------------- ------------------ ------------------------ --------
Z9xxx94 C C_FK P_PK ENABLED



SQL> truncate table c;

Table truncated.

SQL> truncate table p;
truncate table p
*
ERROR at line 1:
ORA-02266: unique/primary keys in table referenced by enabled foreign keys


We have to disable child table FK constraint first:


SQL> alter table c modify constraint C_FK disable;

Table altered.

SQL> truncate table p;

Table truncated.

SQL> alter table c modify constraint C_FK enable;

Table altered.

SQL> select count(*) from c;

COUNT(*)
----------
0

SQL> select count(*) from p;

COUNT(*)
----------
0