Oracle 为什么没有提出我的例外?
我不熟悉PL/SQL和Oracle。我正在处理一个小代码块,它生成列中前5个值。我试图在表中的数据行少于5行时引发一个异常Oracle 为什么没有提出我的例外?,oracle,plsql,exception-handling,Oracle,Plsql,Exception Handling,我不熟悉PL/SQL和Oracle。我正在处理一个小代码块,它生成列中前5个值。我试图在表中的数据行少于5行时引发一个异常 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
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;
/
我只插入了2行数据,但它仍在处理所有数据。为什么?下面是一个示例,您可以通过查询游标属性来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.
但我强调,这不是一种聪明的做事方式,尽管如果这是你的任务,那就好了。通常,我们会尽可能地使用SQL来保持代码的简洁性,并且我们从不希望在其他错误出现时捕获所有错误,而不将它们传播回调用环境。因此,您还可以按如下方式重新编写代码:
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
您希望提出哪种例外情况?循环结束是因为第二次迭代后退出,但这不是一个例外。循环结束后,光标仍然关闭,没有异常,块结束。我试图引发其他错误。所以我需要将我的异常放在for循环中?这段代码不会引发异常,无论您将检查放在哪里。如果要在少于5行时引发异常,请在循环中添加一个变量,并在每次迭代时递增该变量;然后,就在循环外部,您可以检查该变量的值,如果该值小于5,则引发异常raise_应用程序_错误。然而,我认为这是一种练习,因为我会用一种完全不同的方法来做你想做的事情need@Aleksej是的,这是一个课堂练习。提出了使用光标循环的不同方法。