sql - 变异，触发器/函数可能看不到它-触发器执行期间的错误

Question

CREATE OR REPLACE TRIGGER UPDATE_TEST_280510
AFTER insert on TEST_TRNCOMPVISIT
declare
V_TRNCOMPNO NUMBER(10);

CURSOR C1 IS SELECT B.COMPNO FROM TEST_TRNCOMPVISIT A, TEST_TRNCOMPMST B, 
                                  TEST_MEMMAST C
WHERE A.COMPNO=B.COMPNO 
AND B.TRNMEMID=C.MEMID 
AND C.MEMOS>=1000;

begin
open c1;
fetch c1 into V_TRNCOMPNO;


UPDATE TEST_TRNCOMPMST SET COMPSTATUS='P',
       remark='comp is pending due to O/S>1000'
WHERE COMPNO=V_TRNCOMPNO AND COMPSTATUS='C';
CLOSE C1;

end;

我做了这个触发器，当在表中插入行时 - TEST_TRNCOMPVISIT 它给出以下错误 -

发生了以下错误:

ORA-04091: table TEST.TEST_TRNCOMPVISIT is mutating, trigger/function may not see it
ORA-06512: at "TEST.UPDATE_TEST_280510", line 4
ORA-06512: at "TEST.UPDATE_TEST_280510", line 10
ORA-04088: error during execution of trigger 'TEST.UPDATE_TEST_280510'

Answer 1

当定义为 FOR EACH ROW 的触发器尝试访问为其触发的表时，会引发“表正在改变”异常。 Tom Kyte 撰写了有关此异常的原因和解决方法的出色指南 here .

在您发布的示例中，您没有 FOR EACH ROW，因此我不希望引发异常。通常只有在需要访问每一行的 :OLD 或 :NEW 值的情况下才需要使用 FOR EACH ROW 触发器，而您不需要。