[英]Why is my exception not being raised?
我是PL / SQL和Oracle的新手。 我正在研究一个小的代码块,该代码块在列中生成前5个值。 我试图在表中少于5行数据时引发异常。
DELETE FROM CREDIT_CARD;
SELECT * FROM CREDIT_CARD;
Insert into CREDIT_CARD values (6011956844573649,'550',892);
Insert into CREDIT_CARD values (5250335443644204,'15000',661);
DECLARE
CURSOR Final_Q2_Cursor is
SELECT CREDITCARDNUMBER,CREDITCARDLIMIT,CUSTOMERID FROM CREDIT_CARD
ORDER BY CREDITCARDLIMIT DESC; -- start with highest paid employee
aCardLimt NUMBER(8,2);
aCardNum NUMBER(16);
aCustId INT;
BEGIN
OPEN Final_Q2_Cursor ;
FOR i IN 1..5 LOOP
FETCH Final_Q2_Cursor INTO aCardNum, aCardLimt, aCustId;
EXIT WHEN Final_Q2_Cursor%NOTFOUND;
INSERT INTO TOP_FIVE_CREDIT_LIMITS VALUES (aCardLimt, aCardNum, aCustId);
END LOOP;
CLOSE Final_Q2_Cursor;
EXCEPTION
WHEN no_data_found THEN
dbms_output.put_line('No such customer!');
WHEN others THEN
dbms_output.put_line('Error!');
END;
/
我只插入2行数据,但它仍在处理所有数据。 为什么?
这是一个示例,在其中查询cursor属性以确定是否需要显式引发错误
SQL> create table TOP_FIVE_CREDIT_LIMITS (CREDITCARDLIMIT int, CREDITCARDNUMBER int, CUSTOMERID int );
Table created.
SQL> create table CREDIT_CARD (
2 CREDITCARDNUMBER int,CREDITCARDLIMIT int,CUSTOMERID int );
Table created.
SQL>
SQL> DELETE FROM CREDIT_CARD;
0 rows deleted.
SQL> SELECT * FROM CREDIT_CARD;
no rows selected
SQL> Insert into CREDIT_CARD values (6011956844573649,'550',892);
1 row created.
SQL> Insert into CREDIT_CARD values (5250335443644204,'15000',661);
1 row created.
SQL>
PL / SQL:
SQL> set serverout on
SQL> DECLARE
2 CURSOR Final_Q2_Cursor is
3 SELECT CREDITCARDNUMBER,CREDITCARDLIMIT,CUSTOMERID FROM CREDIT_CARD
4 ORDER BY CREDITCARDLIMIT DESC; -- start with highest paid employee
5
6 aCardLimt NUMBER(8,2);
7 aCardNum NUMBER(16);
8 aCustId INT;
9 BEGIN
10 OPEN Final_Q2_Cursor ;
11 FOR i IN 1..5 LOOP
12 FETCH Final_Q2_Cursor INTO aCardNum, aCardLimt, aCustId;
13
14 if Final_Q2_Cursor%NOTFOUND and i < 5 then
15 raise_application_error(-20000,'Ran out of rows before I got to 5');
16 end if;
17 EXIT WHEN Final_Q2_Cursor%NOTFOUND;
18 INSERT INTO TOP_FIVE_CREDIT_LIMITS VALUES (aCardLimt, aCardNum, aCustId);
19 END LOOP;
20 CLOSE Final_Q2_Cursor;
21 EXCEPTION
22 WHEN no_data_found THEN
23 dbms_output.put_line('No such customer!');
24 WHEN others THEN
25 dbms_output.put_line('Error!');
26 END;
27 /
Error!
PL/SQL procedure successfully completed.
但我要强调的是,这不是一种明智的处理方式(尽管如果您的任务是……那么可以)。 通常,我们尽可能地使用SQL来尝试保持代码的美观和精简,并且我们永远不希望在when-others中捕获所有错误而不将其传播回调用环境。 因此,您还可以像下面这样重铸代码:
SQL> set serverout on
SQL> BEGIN
2 insert into TOP_FIVE_CREDIT_LIMITS
3 select *
4 from
5 ( SELECT CREDITCARDNUMBER,CREDITCARDLIMIT,CUSTOMERID FROM CREDIT_CARD
6 ORDER BY CREDITCARDLIMIT DESC
7 )
8 where rownum <= 5;
9
10 if sql%rowcount = 0 then
11 raise_application_error(-20000,'No rows were found at all');
12 elsif sql%rowcount < 5 then
13 raise_application_error(-20000,'Ran out of rows before I got to 5');
14 end if;
15
16 END;
17 /
BEGIN
*
ERROR at line 1:
ORA-20000: Ran out of rows before I got to 5
ORA-06512: at line 13
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