Oracle错误:无法在查询中执行DML

Question

为什么我会收到以下错误？

Error starting at line 1 in command:

select FUNC from dual
Error report:
SQL Error: ORA-14551: cannot perform a DML operation inside a query 
ORA-06512: at "ANONYMOUS.FUNC", line 15
14551. 00000 -  "cannot perform a DML operation inside a query "
*Cause:    DML operation like insert, update, delete or select-for-update
           cannot be performed inside a query or under a PDML slave.
*Action:   Ensure that the offending DML operation is not performed or
           use an autonomous transaction to perform the DML operation within
           the query or PDML slave.

功能:

create or replace function FUNC
return types.ref_cursor
AS
result_set types.ref_cursor;
alarm ofalarmmessages.ALARMID% TYPE;
username ofalarmmessages.USERNAME% TYPE;
alarmmsg ofalarmmessages.ALARMMESSAGE% TYPE;
dvice ofalarmmessages.DEVICEID% TYPE;
begin
OPEN result_set FOR
       SELECT USERNAME,ALARMID,ALARMMESSAGE,DEVICEID
    FROM   ofalarmmessages where newoldflag='N';
LOOP
    FETCH  result_set into username,alarm,alarmmsg,dvice;
        update ofalarmmessages set newoldflag ='Y' where alarmid= alarm;
END LOOP;
RETURN result_set;
CLOSE result_set;
END;
/
show errors;

Answer 1

这里有两个问题.您收到'ORA-14551'错误,因为您正在SELECT语句中执行您的函数,并且正如错误消息清楚地指出的那样,当函数执行DML时,我们无法执行此操作.此问题的解决方案是在PL/SQL或SQL*Plus中执行它.

另一个问题是引用游标是指向结果集的指针,只能获取一次.您的函数遍历引用游标,然后返回它.当您尝试对返回的引用游标执行某些操作时,这将导致错误,因为它不再有效.

哦,顺便说一句,函数中任何跟随RETURN语句的代码都不会被执行.