Question

复合触发器有问题。：当指定部分之后的部分时，new.value在每行部分之前的中为空/空。

创建表格部分：

DROP TABLE test_tab; CREATE TABLE test_tab ( ID_TEST_TAB NUMBER ); INSERT INTO test_tab VALUES (1 ); INSERT INTO test_tab VALUES (2 );

触发器的部分：

CREATE OR REPLACE TRIGGER TEST_COMP_TRIGGER FOR UPDATE ON test_tab COMPOUND TRIGGER --- BEFORE EACH ROW IS BEGIN dbms_output.put_line('TEST_COMP_TRIGGER: BEFORE EACH ROW'); dbms_output.put_line('>>>> old: ' || :old.ID_TEST_TAB ); dbms_output.put_line('>>>> new: ' || :new.ID_TEST_TAB ); NULL; END BEFORE EACH ROW; --- AFTER STATEMENT IS BEGIN NULL; END AFTER STATEMENT; END TEST_COMP_TRIGGER; /

后：

UPDATE test_tab SET test_tab.ID_TEST_TAB=test_tab.ID_TEST_TAB;

我明白了：

TEST_COMP_TRIGGER: BEFORE EACH ROW >>>> old: 1 >>>> new: TEST_COMP_TRIGGER: BEFORE EACH ROW >>>> old: 2 >>>> new:

如果省略之后的部分，结果是正确的：

CREATE OR REPLACE TRIGGER TEST_COMP_TRIGGER FOR UPDATE ON test_tab COMPOUND TRIGGER --- BEFORE EACH ROW IS BEGIN dbms_output.put_line('TEST_COMP_TRIGGER: BEFORE EACH ROW'); dbms_output.put_line('>>>> old: ' || :old.ID_TEST_TAB ); dbms_output.put_line('>>>> new: ' || :new.ID_TEST_TAB ); NULL; END BEFORE EACH ROW; END TEST_COMP_TRIGGER; /

后：

UPDATE test_tab SET test_tab.ID_TEST_TAB=test_tab.ID_TEST_TAB;

我明白了：

TEST_COMP_TRIGGER: BEFORE EACH ROW >>>> old: 1 >>>> new: 2 TEST_COMP_TRIGGER: BEFORE EACH ROW >>>> old: 2 >>>> new: 2

为什么在第一种情况下：new.value是空白的？

-----------更新我按照你的指示：代码：

create or replace trigger TEST_COMP_TRIGGER FOR UPDATE ON test_tab COMPOUND TRIGGER ---- BEFORE BEFORE STATEMENT IS BEGIN dbms_output.put_line('TEST_COMP_TRIGGER: BEFORE STATEMENT'); NULL; END BEFORE STATEMENT; ---- AFTER AFTER STATEMENT IS BEGIN dbms_output.put_line('TEST_COMP_TRIGGER: AFTER STATEMENT'); NULL; END AFTER STATEMENT; ---- BEFORE EACH BEFORE EACH ROW IS BEGIN dbms_output.put_line('TEST_COMP_TRIGGER: BEFORE EACH ROW'); dbms_output.put_line('>>>> old: ' || :old.ID_TEST_TAB ); dbms_output.put_line('>>>> new: ' || :new.ID_TEST_TAB ); NULL; END BEFORE EACH ROW; END TEST_COMP_TRIGGER; / ----- SET serveroutput ON format wraped; UPDATE test_tab SET test_tab.ID_TEST_TAB=test_tab.ID_TEST_TAB; /

给出预期结果：

2 rows updated. TEST_COMP_TRIGGER: BEFORE STATEMENT TEST_COMP_TRIGGER: BEFORE EACH ROW >>>> old: 1 >>>> new: 1 TEST_COMP_TRIGGER: BEFORE EACH ROW >>>> old: 2 >>>> new: 2 TEST_COMP_TRIGGER: AFTER STATEMENT

但是当我添加AFTER EACH ROW声明时：

create or replace trigger TEST_COMP_TRIGGER FOR UPDATE ON test_tab COMPOUND TRIGGER ---- BEFORE BEFORE STATEMENT IS BEGIN dbms_output.put_line('TEST_COMP_TRIGGER: BEFORE STATEMENT'); NULL; END BEFORE STATEMENT; ---- AFTER AFTER STATEMENT IS BEGIN dbms_output.put_line('TEST_COMP_TRIGGER: AFTER STATEMENT'); NULL; END AFTER STATEMENT; ---- BEFORE EACH BEFORE EACH ROW IS BEGIN dbms_output.put_line('TEST_COMP_TRIGGER: BEFORE EACH ROW'); dbms_output.put_line('>>>> old: ' || :old.ID_TEST_TAB ); dbms_output.put_line('>>>> new: ' || :new.ID_TEST_TAB ); NULL; END BEFORE EACH ROW; ---- AFTER EACH AFTER EACH ROW IS BEGIN dbms_output.put_line('TEST_COMP_TRIGGER: AFTER EACH ROW'); END AFTER EACH ROW; END TEST_COMP_TRIGGER; / ----- SET serveroutput ON format wraped; UPDATE test_tab SET test_tab.ID_TEST_TAB=test_tab.ID_TEST_TAB; /

我还是空着：新：

2 rows updated. TEST_COMP_TRIGGER: BEFORE STATEMENT TEST_COMP_TRIGGER: BEFORE EACH ROW >>>> old: 1 >>>> new: TEST_COMP_TRIGGER: AFTER EACH ROW TEST_COMP_TRIGGER: BEFORE EACH ROW >>>> old: 2 >>>> new: TEST_COMP_TRIGGER: AFTER EACH ROW TEST_COMP_TRIGGER: AFTER STATEMENT

Answer 1

时间点部分的顺序很重要，需要：

BEFORE STATEMENT
AFTER STATEMENT
BEFORE EACH ROW
AFTER EACH ROW

参考：Compound Trigger Sections, Oracle 11gR1 docs

以下脚本（在Oracle SQL Developer中运行，连接到Oracle Database 11g Express Edition Release 11.2.0.2.0 - Production

DROP TABLE test_tab;
CREATE TABLE test_tab ( ID_TEST_TAB NUMBER);
INSERT INTO test_tab VALUES (1);
INSERT INTO test_tab VALUES (2);

create or replace trigger TEST_COMP_TRIGGER
FOR UPDATE ON test_tab  
COMPOUND TRIGGER   

  AFTER STATEMENT IS
  BEGIN
    dbms_output.put_line('TEST_COMP_TRIGGER:  AFTER STATEMENT');
    NULL;
  END AFTER STATEMENT;

  BEFORE EACH ROW IS
  BEGIN
    dbms_output.put_line('TEST_COMP_TRIGGER:  BEFORE EACH ROW');
    dbms_output.put_line('>>>> old: ' || :old.ID_TEST_TAB );
    dbms_output.put_line('>>>> new: ' || :new.ID_TEST_TAB );
    NULL;
  END BEFORE EACH ROW;

END TEST_COMP_TRIGGER;
/

set serveroutput on format wraped;
UPDATE test_tab SET test_tab.ID_TEST_TAB=test_tab.ID_TEST_TAB+1;
/

产生输出：

table TEST_TAB dropped.
table TEST_TAB created.
1 rows inserted.
1 rows inserted.
TRIGGER TEST_COMP_TRIGGER compiled
2 rows updated.
TEST_COMP_TRIGGER:  BEFORE EACH ROW
>>>> old: 1
>>>> new: 2
TEST_COMP_TRIGGER:  BEFORE EACH ROW
>>>> old: 2
>>>> new: 3
TEST_COMP_TRIGGER:  AFTER STATEMENT

将它们换成错误的顺序，输出结束为：

table TEST_TAB dropped.
table TEST_TAB created.
1 rows inserted.
1 rows inserted.
TRIGGER TEST_COMP_TRIGGER compiled
2 rows updated.
TEST_COMP_TRIGGER:  BEFORE EACH ROW
>>>> old: 1
>>>> new: 
TEST_COMP_TRIGGER:  BEFORE EACH ROW
>>>> old: 2
>>>> new: 
TEST_COMP_TRIGGER:  AFTER STATEMENT

Answer 2

以下脚本按预期工作。

DROP TABLE test_tab;
CREATE TABLE test_tab ( IDNO NUMBER);
INSERT INTO test_tab VALUES (1);
INSERT INTO test_tab VALUES (2);

create or replace trigger TEST_COMP_TRIGGER
FOR UPDATE ON test_tab  
COMPOUND TRIGGER   
---- BEFORE
  BEFORE STATEMENT IS
  BEGIN
    dbms_output.put_line('TEST_COMP_TRIGGER:  BEFORE STATEMENT');
  END BEFORE STATEMENT;
---- AFTER
  AFTER STATEMENT IS
  BEGIN
    dbms_output.put_line('TEST_COMP_TRIGGER:  AFTER STATEMENT');
  END AFTER STATEMENT;
---- BEFORE EACH
  BEFORE EACH ROW IS
  BEGIN
    dbms_output.put('TEST_COMP_TRIGGER:  BEFORE EACH ROW');
    dbms_output.put(' old: ' || :old.IDNO || ' new: ' || :new.IDNO);
    :New.IDNO := :new.IDNO + 1;
    dbms_output.put_line(' old: ' || :old.IDNO || ' new: ' || :new.IDNO);
  END BEFORE EACH ROW;
---- AFTER EACH  
  AFTER EACH ROW IS
  BEGIN
    dbms_output.put('TEST_COMP_TRIGGER:  AFTER EACH ROW');
    dbms_output.put_line(' old: ' || :old.IDNO || ' new: ' || :new.IDNO);
  END AFTER EACH ROW;
END TEST_COMP_TRIGGER;
/

set serveroutput on format wraped;
UPDATE test_tab SET test_tab.IDNO=test_tab.IDNO+1;
/

生成输出：

table TEST_TAB dropped.
table TEST_TAB created.
1 rows inserted.
1 rows inserted.
TRIGGER TEST_COMP_TRIGGER compiled
2 rows updated.
TEST_COMP_TRIGGER:  BEFORE STATEMENT
TEST_COMP_TRIGGER:  BEFORE EACH ROW old: 1 new: 2 old: 1 new: 3
TEST_COMP_TRIGGER:  AFTER EACH ROW old: 1 new: 3
TEST_COMP_TRIGGER:  BEFORE EACH ROW old: 2 new: 3 old: 2 new: 4
TEST_COMP_TRIGGER:  AFTER EACH ROW old: 2 new: 4
TEST_COMP_TRIGGER:  AFTER STATEMENT

现在为了好玩。

在AFTER EACH ROW中使用绑定变量注释掉该行，你得到空白：每个行前的新绑定变量
重新排序这些部分可以让它再次起作用，例如将每个行后移动到触发器的顶部
某些排序为空白：NEW没有任何行注释掉（在声明之前，行之前，行之后，例如声明之后）

非常挑剔和奇怪的行为。

如何检查：复合触发器中的新值，何时指定after语句？

2 个答案: