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下列的哪些程序块在执行之后会显示:"Trapped!"
注意:当你试图把字符串 "13-DEC-2004 6:56 PM" 使用掩码 "DD-MON-YYYY HH:MI:SS" 转换成日期型时,Oracle 会抛出 ORA-01858 错误。
(A)
DECLARE e1 EXCEPTION; PRAGMA EXCEPTION_INIT (e1, -1858); BEGIN DBMS_OUTPUT.put_line ( TO_DATE ('13-DEC-2004 6:56 PM' , 'DD-MON-YYYY HH:MI:SS')); EXCEPTION WHEN e1 THEN DBMS_OUTPUT.put_line ('Trapped!'); END; /
SQL> DECLARE 2 e1 EXCEPTION; 3 PRAGMA EXCEPTION_INIT (e1, -1858); 4 BEGIN 5 DBMS_OUTPUT.put_line ( 6 TO_DATE ('13-DEC-2004 6:56 PM' 7 , 'DD-MON-YYYY HH:MI:SS')); 8 EXCEPTION 9 WHEN e1 10 THEN 11 DBMS_OUTPUT.put_line ('Trapped!'); 12 END; 13 / DECLARE e1 EXCEPTION; PRAGMA EXCEPTION_INIT (e1, -1858); BEGIN DBMS_OUTPUT.put_line ( TO_DATE ('13-DEC-2004 6:56 PM' , 'DD-MON-YYYY HH:MI:SS')); EXCEPTION WHEN e1 THEN DBMS_OUTPUT.put_line ('Trapped!'); END; ORA-01843: 无效的月份 ORA-06512: 在 line 5 SQL>
(B)
DECLARE e1 EXCEPTION; PRAGMA EXCEPTION_INIT (e1, -1858); BEGIN DECLARE e2 EXCEPTION; PRAGMA EXCEPTION_INIT (e2, -1858); BEGIN DBMS_OUTPUT.put_line ( TO_DATE ('13-DEC-2004 6:56 PM' , 'DD-MON-YYYY HH:MI:SS')); END; EXCEPTION WHEN e1 THEN DBMS_OUTPUT.put_line ('Trapped!'); END; /
SQL> DECLARE 2 e1 EXCEPTION; 3 PRAGMA EXCEPTION_INIT (e1, -1858); 4 BEGIN 5 DECLARE 6 e2 EXCEPTION; 7 PRAGMA EXCEPTION_INIT (e2, -1858); 8 BEGIN 9 DBMS_OUTPUT.put_line ( 10 TO_DATE ('13-DEC-2004 6:56 PM' 11 , 'DD-MON-YYYY HH:MI:SS')); 12 END; 13 EXCEPTION 14 WHEN e1 15 THEN 16 DBMS_OUTPUT.put_line ('Trapped!'); 17 END; 18 / DECLARE e1 EXCEPTION; PRAGMA EXCEPTION_INIT (e1, -1858); BEGIN DECLARE e2 EXCEPTION; PRAGMA EXCEPTION_INIT (e2, -1858); BEGIN DBMS_OUTPUT.put_line ( TO_DATE ('13-DEC-2004 6:56 PM' , 'DD-MON-YYYY HH:MI:SS')); END; EXCEPTION WHEN e1 THEN DBMS_OUTPUT.put_line ('Trapped!'); END; ORA-01843: 无效的月份 ORA-06512: 在 line 9 SQL>
(C)
DECLARE e1 EXCEPTION; PRAGMA EXCEPTION_INIT (e1, -1858); BEGIN DECLARE e2 EXCEPTION; PRAGMA EXCEPTION_INIT (e2, -1858); BEGIN DBMS_OUTPUT.put_line ( TO_DATE ('13-DEC-2004 6:56 PM' , 'DD-MON-YYYY HH:MI:SS')); END; EXCEPTION WHEN e2 THEN DBMS_OUTPUT.put_line ('Trapped!'); END; /
SQL> DECLARE 2 e1 EXCEPTION; 3 PRAGMA EXCEPTION_INIT (e1, -1858); 4 BEGIN 5 DECLARE 6 e2 EXCEPTION; 7 PRAGMA EXCEPTION_INIT (e2, -1858); 8 BEGIN 9 DBMS_OUTPUT.put_line ( 10 TO_DATE ('13-DEC-2004 6:56 PM' 11 , 'DD-MON-YYYY HH:MI:SS')); 12 END; 13 EXCEPTION 14 WHEN e2 15 THEN 16 DBMS_OUTPUT.put_line ('Trapped!'); 17 END; 18 / DECLARE e1 EXCEPTION; PRAGMA EXCEPTION_INIT (e1, -1858); BEGIN DECLARE e2 EXCEPTION; PRAGMA EXCEPTION_INIT (e2, -1858); BEGIN DBMS_OUTPUT.put_line ( TO_DATE ('13-DEC-2004 6:56 PM' , 'DD-MON-YYYY HH:MI:SS')); END; EXCEPTION WHEN e2 THEN DBMS_OUTPUT.put_line ('Trapped!'); END; ORA-06550: 第 14 行, 第 9 列: PLS-00201: 必须声明标识符 'E2' ORA-06550: 第 0 行, 第 0 列: PL/SQL: Compilation unit analysis terminated SQL>
(D)
DECLARE e1 EXCEPTION; BEGIN DECLARE PRAGMA EXCEPTION_INIT (e1, -1858); BEGIN DBMS_OUTPUT.put_line ( TO_DATE ('13-DEC-2004 6:56 PM' , 'DD-MON-YYYY HH:MI:SS')); END; EXCEPTION WHEN e1 THEN DBMS_OUTPUT.put_line ('Trapped!'); END; /
SQL> DECLARE 2 e1 EXCEPTION; 3 BEGIN 4 DECLARE 5 PRAGMA EXCEPTION_INIT (e1, -1858); 6 BEGIN 7 DBMS_OUTPUT.put_line ( 8 TO_DATE ('13-DEC-2004 6:56 PM' 9 , 'DD-MON-YYYY HH:MI:SS')); 10 END; 11 EXCEPTION 12 WHEN e1 13 THEN 14 DBMS_OUTPUT.put_line ('Trapped!'); 15 END; 16 / DECLARE e1 EXCEPTION; BEGIN DECLARE PRAGMA EXCEPTION_INIT (e1, -1858); BEGIN DBMS_OUTPUT.put_line ( TO_DATE ('13-DEC-2004 6:56 PM' , 'DD-MON-YYYY HH:MI:SS')); END; EXCEPTION WHEN e1 THEN DBMS_OUTPUT.put_line ('Trapped!'); END; ORA-06550: 第 2 行, 第 4 列: PLS-00700: 'E1' 的 PRAGMA EXCEPTION_INIT 必须在同一个声明部分中的异常错误声明之后 ORA-06550: 第 5 行, 第 7 列: PL/SQL: Item ignored SQL>
结果有出入,设置语言为英文后重跑
SQL> alter session set nls_language='american'; Session altered SQL> SQL> DECLARE 2 e1 EXCEPTION; 3 PRAGMA EXCEPTION_INIT (e1, -1858); 4 BEGIN 5 DBMS_OUTPUT.put_line ( 6 TO_DATE ('13-DEC-2004 6:56 PM' 7 , 'DD-MON-YYYY HH:MI:SS')); 8 EXCEPTION 9 WHEN e1 10 THEN 11 DBMS_OUTPUT.put_line ('Trapped!'); 12 END; 13 / Trapped! PL/SQL procedure successfully completed SQL>
SQL> alter session set nls_language='american'; Session altered SQL> SQL> SQL> DECLARE 2 e1 EXCEPTION; 3 PRAGMA EXCEPTION_INIT (e1, -1858); 4 BEGIN 5 DECLARE 6 e2 EXCEPTION; 7 PRAGMA EXCEPTION_INIT (e2, -1858); 8 BEGIN 9 DBMS_OUTPUT.put_line ( 10 TO_DATE ('13-DEC-2004 6:56 PM' 11 , 'DD-MON-YYYY HH:MI:SS')); 12 END; 13 EXCEPTION 14 WHEN e1 15 THEN 16 DBMS_OUTPUT.put_line ('Trapped!'); 17 END; 18 / Trapped! PL/SQL procedure successfully completed SQL>
SQL> alter session set nls_language='american'; Session altered SQL> SQL> SQL> DECLARE 2 e1 EXCEPTION; 3 PRAGMA EXCEPTION_INIT (e1, -1858); 4 BEGIN 5 DECLARE 6 e2 EXCEPTION; 7 PRAGMA EXCEPTION_INIT (e2, -1858); 8 BEGIN 9 DBMS_OUTPUT.put_line ( 10 TO_DATE ('13-DEC-2004 6:56 PM' 11 , 'DD-MON-YYYY HH:MI:SS')); 12 END; 13 EXCEPTION 14 WHEN e2 15 THEN 16 DBMS_OUTPUT.put_line ('Trapped!'); 17 END; 18 / DECLARE e1 EXCEPTION; PRAGMA EXCEPTION_INIT (e1, -1858); BEGIN DECLARE e2 EXCEPTION; PRAGMA EXCEPTION_INIT (e2, -1858); BEGIN DBMS_OUTPUT.put_line ( TO_DATE ('13-DEC-2004 6:56 PM' , 'DD-MON-YYYY HH:MI:SS')); END; EXCEPTION WHEN e2 THEN DBMS_OUTPUT.put_line ('Trapped!'); END; ORA-06550: line 14, column 9: PLS-00201: identifier 'E2' must be declared ORA-06550: line 0, column 0: PL/SQL: Compilation unit analysis terminated SQL>
SQL> alter session set nls_language='american'; Session altered SQL> SQL> SQL> DECLARE 2 e1 EXCEPTION; 3 BEGIN 4 DECLARE 5 PRAGMA EXCEPTION_INIT (e1, -1858); 6 BEGIN 7 DBMS_OUTPUT.put_line ( 8 TO_DATE ('13-DEC-2004 6:56 PM' 9 , 'DD-MON-YYYY HH:MI:SS')); 10 END; 11 EXCEPTION 12 WHEN e1 13 THEN 14 DBMS_OUTPUT.put_line ('Trapped!'); 15 END; 16 / DECLARE e1 EXCEPTION; BEGIN DECLARE PRAGMA EXCEPTION_INIT (e1, -1858); BEGIN DBMS_OUTPUT.put_line ( TO_DATE ('13-DEC-2004 6:56 PM' , 'DD-MON-YYYY HH:MI:SS')); END; EXCEPTION WHEN e1 THEN DBMS_OUTPUT.put_line ('Trapped!'); END; ORA-06550: line 2, column 4: PLS-00700: PRAGMA EXCEPTION_INIT of E1 must follow declaration of its exception in the same declarative part ORA-06550: line 5, column 7: PL/SQL: Item ignored SQL>
答案AB(设置语言为英文,则答案AB;如语言为中文,答案均不正确)
答案说明74楼
A: 正确捕获-1858异常 B: 内层也定义了-1858但是没有捕获,所以外层仍然能够捕获到 C: 内层的定义在外层是不可见的,会报PLS-00201: identifier 'E2' must be declared D: PRAGMA EXCEPTION_INIT必须和EXCEPTION定义在同一层DECLARE中: PLS-00700: PRAGMA EXCEPTION_INIT of E1 must follow declaration of its exception in the same declarative part
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