Question

是否可以在Oracle中触发器内创建或替换视图？

视图是通过连接2个表创建的，其中一个是触发器更新的表

Answer 1

只是为了提供所有选项（但是在触发器内创建视图的想法可能很奇怪......）你可以在触发器中创建一个视图。是的，隐式COMMIT将会跟随，但如果我们使触发器在自治事务中工作，那么动态DDL将不会失败。使用Luke Woodward的例子：

CREATE TABLE test (a integer);

INSERT INTO test (a) VALUES (5);

CREATE OR REPLACE TRIGGER test_trig
  AFTER UPDATE ON test
  FOR EACH ROW
DECLARE
  -- making the trigger work outside of the main transaction
  PRAGMA autonomous_transaction;
BEGIN
    EXECUTE IMMEDIATE 'CREATE OR REPLACE VIEW test_view AS SELECT * FROM test';
END;
/

UPDATE test SET a = 6;

SELECT * FROM test_view;

         A
----------
         6

Check at SQLFiddle

Answer 2

不，你不能。创建视图会强制提交，并且您无法在触发器中提交。

以下是您尝试执行此操作时会发生的情况：

SQL> CREATE TABLE test (a integer);

Table created.

SQL> INSERT INTO test (a) VALUES (5);

1 row created.

SQL> COMMIT;

Commit complete.

SQL> CREATE OR REPLACE TRIGGER test_trig
  2    AFTER UPDATE ON test
  3    FOR EACH ROW
  4  BEGIN
  5    EXECUTE IMMEDIATE 'CREATE OR REPLACE VIEW test_view AS SELECT * FROM test';
  6  END;
  7  /

Trigger created.

SQL> UPDATE test SET a = 6;
UPDATE test SET a = 6
       *
ERROR at line 1:
ORA-04092: cannot COMMIT in a trigger
ORA-06512: at "LUKE.TEST_TRIG", line 2
ORA-04088: error during execution of trigger 'LUKE.TEST_TRIG'

在触发器体内创建视图 - Oracle

2 个答案: