PL/SQL 如何修复进程标志 id=4 错误打印以及如何显示错误消息

Question

创建表

create table curexample_test (id number, x number, y number, result number, process_flag varchar2(1), error_message varchar2(400))

insert into curexample_test
select 1, 20,4,null,null,null from dual
union
select 2, 15,3,null,null,null from dual
union
select 3, 36,9,null,null,null from dual
union
select 4, 7,0,null,null,null from dual
union
select 5, 105,15,null,null,null from dual

select * from curexample_test

创建函数

create or replace function divider(n1 in number, n2 in number)    
        return number    
            is     
            pragma autonomous_transaction;
            n3 number;    
         begin    
             
            if n2 = 0 then
               n3 :=null; 

                 update curexample_test set process_flag = 'E' where n3 = null ;
              
            else
                n3 :=n1 / n2; 
                 update curexample_test set process_flag = 'S' where n3 !=0 ;
        end if;
            COMMIT;
    return n3;    
        end;  

调用函数

select id,x,y , divider(x,y) as result,process_flag,error_message from curexample_test;

Answer 1

我们很少在函数中执行 DML；如果必须这样做，请使用程序。

从您的代码开始：

• UPDATE 语句中的 WHERE 子句必须修复
• 如果要存储 RESULT，请同时修复 SET 子句
• 如果您将某些东西与NULL 进行比较，那么它不是例如where n3 = null 但where n3 IS NULL

---

SQL> CREATE OR REPLACE FUNCTION divider (n1 IN NUMBER, n2 IN NUMBER)
  2     RETURN NUMBER
  3  IS
  4     PRAGMA AUTONOMOUS_TRANSACTION;
  5
  6     n3  NUMBER;
  7  BEGIN
  8     IF n2 = 0
  9     THEN
 10        n3 := NULL;
 11
 12        UPDATE curexample_test
 13           SET result = n3, process_flag = 'E'
 14         --WHERE n3 = NULL;
 15         WHERE     x = n1
 16               AND y = n2;
 17     ELSE
 18        n3 := n1 / n2;
 19
 20        UPDATE curexample_test
 21           SET result = n3, process_flag = 'S'
 22         -- WHERE n3 != 0;
 23         WHERE     x = n1
 24               AND y = n2;
 25     END IF;
 26
 27     COMMIT;
 28     RETURN n3;
 29  END;
 30  /

Function created.

测试：

SQL> SELECT id,
  2         x,
  3         y,
  4         divider (x, y) AS result,
  5         process_flag,
  6         error_message
  7    FROM curexample_test;

        ID          X          Y     RESULT PROCESS_FLAG    ERROR_MESSAGE
---------- ---------- ---------- ---------- --------------- --------------------
         1         20          4          5
         2         15          3          5
         3         36          9          4
         4          7          0
         5        105         15          7

然后是表格内容

SQL> select * from curexample_test;

        ID          X          Y     RESULT PROCESS_FLAG    ERROR_MESSAGE
---------- ---------- ---------- ---------- --------------- --------------------
         1         20          4          5 S
         2         15          3          5 S
         3         36          9          4 S
         4          7          0            E
         5        105         15          7 S

SQL>