在之前的版本中,存在外键约束时,无法直接truncate父表。在12C中,对truncate操作添加了级联操作特性。
前提是创建外键约束时,使用了"on delete casacde"。
测试脚本:
SQL> drop table child; SQL> drop table parent; SQL> create table parent(id number primary key); SQL> create table child(cid number primary key,pid number); SQL> alter table child add constraint fk_parent_child foreign key(pid) references parent(id) on delete cascade; SQL> insert into parent values(1); SQL> insert into parent values(2); SQL> insert into child values(1,1); SQL> insert into child values(2,1); SQL> insert into child values(3,2); SQL> commit; SQL> select a.id,b.cid,b.pid from parent a, child b where a.id=b.pid; ID CID PID ---------- ---------- ---------- 1 1 1 1 2 1 2 3 2 SQL>
11gR2的测试结果:
SQL> truncate table parent cascade; truncate table parent cascade * ERROR at line 1: ORA-03291: Invalid truncate option - missing STORAGE keyword SQL>
12C的测试结果:
SQL> truncate table parent cascade;
Table truncated.
SQL>