insert into (<select clause> WITH CHECK OPTION) values (...)
例如:
SQL> insert into (select object_id,object_name,object_type from xxx where object_id<1000 WITH CHECK OPTION) 2 values(999,'testbyhao','testtype');
這樣的語法看起來很特殊,其實是insert進subquery裡的這張表裡,只不過如果不滿足subquery裡的where條件的話,就不允許插入。
如果插入的列有不在subquery作為檢查的where條件裡,那麼也會不允許插入。
如果不加WITH CHECK OPTION則在插入時不會檢查。
這裡注意,subquery其實是不會實際執行的。
例如:
SQL> insert into (select object_id,object_name,object_type from xxx where object_id<1000) 2 values(1001,'testbyhao','testtype'); 1 row created. SQL> insert into (select object_id,object_name,object_type from xxx where object_id<1000with check option) 2 values(1001,'testbyhao','testtype'); insert into (select object_id,object_name,object_type from xxx where object_id<1000 with check option) * ERROR at line 1: ORA-01402: view WITH CHECK OPTION where-clause violation
這裡插入的列中沒有object_id,也是不允許插入的:
SQL> insert into (select object_name,object_type from xxx where object_id<1000 with check option) 2 values('testbyhao','testtype'); insert into (select object_name,object_type from xxx where object_id<1000 with check option) * ERROR at line 1: ORA-01402: view WITH CHECK OPTION where-clause violation
為什麼說subquery沒有實際執行呢?看統計信息吧:
SQL> set autotrace trace exp stat SQL> select object_id,object_name,object_type from xxx where object_id<1000; 955 rows selected. 97 consistent gets SQL> insert into (select object_id,object_name,object_type from xxx where object_id<1000) 2 values(999,'testbyhao','testtype'); 1 row created. 1 consistent gets