Sqlplus使用存储过程更新一行

Question

这是我目前所拥有的。当我输入有效数据并运行它时，表会正确更新。当我使用我知道表中不存在的作者编号运行它时，它仍然运行，并且不输出异常语句。有谁知道为什么我的例外似乎不起作用。任何帮助将不胜感激谢谢！

CREATE OR REPLACE PROCEDURE update_authorname 
(selected_author_num IN NUMBER, 
new_author_first IN CHAR,
new_author_last IN CHAR) AS 

BEGIN
UPDATE author
SET author_first = new_author_first, author_last = new_author_last
WHERE author_num = selected_author_num;

EXCEPTION
  WHEN NO_DATA_FOUND 
  THEN
  DBMS_OUTPUT.PUT_LINE('No author with this number exists: ' || selected_author_num);

  WHEN ROWTYPE_MISMATCH 
  THEN
  DBMS_OUTPUT.PUT_LINE('Error: There was a row type mismatch when updating');

END;
/

这就是我以前所说的过程：

BEGIN
update_authorname(6,'Emma','White');
END;
/

Answer 1

当where 子句不匹配时，update 语句不会引发异常，它只是静默失败。相反，您需要检查：

1. 尝试更新之前的行exists 或
2. 更新改变了一些东西。

1.该行存在

CREATE OR REPLACE PROCEDURE update_authorname 
(selected_author_num IN NUMBER, 
new_author_first IN CHAR,
new_author_last IN CHAR) AS 

BEGIN

IF NOT EXISTS (SELECT 1 FROM author WHERE author_num = selected_author_num;
  DBMS_OUTPUT.PUT_LINE('No author with this number exists: ' || selected_author_num);
ELSE
  UPDATE author
  SET author_first = new_author_first, author_last = new_author_last
  WHERE author_num = selected_author_num;

EXCEPTION
  WHEN ROWTYPE_MISMATCH 
  THEN
  DBMS_OUTPUT.PUT_LINE('Error: There was a row type mismatch when updating');

END;
/

2。更新进行了更改

CREATE OR REPLACE PROCEDURE update_authorname 
(selected_author_num IN NUMBER, 
new_author_first IN CHAR,
new_author_last IN CHAR) AS 

BEGIN


UPDATE author
SET author_first = new_author_first, author_last = new_author_last
WHERE author_num = selected_author_num;

IF @@ROWCOUNT <= 0
  DBMS_OUTPUT.PUT_LINE('No author with this number exists: ' || selected_author_num);

EXCEPTION
  WHEN ROWTYPE_MISMATCH 
  THEN
  DBMS_OUTPUT.PUT_LINE('Error: There was a row type mismatch when updating');

END;
/

当然还有其他方法可以达到相同的效果，但这是最常见的两种。