触发执行期间出错ORA-06512和ORA-04088

Question

我创建了一个触发器，以便用户在CRIME表中不存在CRIME_NO时不能输入CRIME_NO。我确实收到了犯罪号码：＆＃39; || ：new.CRIME_NO || ＆＃39;不在犯罪表中的错误。

但我也收到ORA-06512：at＆＃34; C3405016.EVIDENCE_FK＆＃34;，第8行ORA-04088：执行触发器时出错＆＃39; C3405016.EVIDENCE_FK＆＃39;

Create or replace trigger Evidence_fk
before insert or update of CRIME_NO
on Evidence
for each row
declare
         dummy   integer;
begin
         select count(*)    into dummy
         from Evidence
         where CRIME_NO = :new.CRIME_NO;
     if (dummy < 1) /* i.e. no corresponding Crime_No in Crime */
             then raise_application_error(-20002,
             'Crime Number: '|| :new.CRIME_NO || ' not in the Crime table');
         end if;
end;

ORA-20002：犯罪号码：20不在犯罪表ORA-06512：at＆＃34; C3405016.EVIDENCE_FK＆＃34;，第8行ORA-04088：执行触发器时出错＆＃39; C3405016.EVIDENCE_FK＆ ＃39;