Question

我试图为书桌编写触发器。对于此表，

create table books (
    isbn VARCHAR(13) CHECK (LENGTH (isbn) = 10 or LENGTH (isbn) = 13),
    ...
    PRIMARY KEY (isbn)
);

我想写一个触发器，当插入长度为10的isbn时，根据以下规则将其格式更改为13位数：

删除最后一位数字
在前面添加了978
添加了由公式计算的检查位

CHECK_BIT =（10 - （x1 + 3 * x2 + x3 + 3 * x4 + ... + x11 + 3 * x12）mod 10）mod 10

代码：

create or replace trigger isbnFormatChange
before insert on books
for each row
begin
  if (length (:new.isbn) = 10) then
    :new.isbn := substr (:new.isbn, 1, 9);
    :new.isbn := concat (978, :new.isbn);
    :new.isbn := concat (:new.isbn, mod ((10 - mod ((to_number (substr (:new.isbn, 1, 1)) + 3 * to_number (substr (:new.isbn, 2, 1)) + to_number (substr (:new.isbn, 3, 1)) + 3 * to_number (substr (:new.isbn, 4, 1)) + to_number (substr (:new.isbn, 5, 1)) + 3 * to_number (substr (:new.isbn, 6, 1)) + to_number (substr (:new.isbn, 7, 1)) + 3 * to_number (substr (:new.isbn, 8, 1)) + to_number (substr (:new.isbn, 9, 1)) + 3 * to_number (substr (:new.isbn, 10, 1)) + to_number (substr (:new.isbn, 11, 1)) + 3 * to_number (substr (:new.isbn, 12, 1))), 10)), 10));
  end if;
end;

但它会出现以下错误：

Error(5,5): PL/SQL: Statement ignored
Error(5,63): PLS-00330: invalid use of type name or subtype name

我认为我做错了第3步（公式部分）

Answer 1

函数convert用于将不同的字符类型相互转换。要将字符串转换为数字，请使用函数to_number。因此，您只需要在代码中将所有convert (int, ...)替换为to_number()函数：

create or replace trigger isbnFormatChange
before insert on books
for each row
begin
  if (length (:new.isbn) = 10) then
    :new.isbn := substr (:new.isbn, 1, 9);
    :new.isbn := concat (978, :new.isbn);
    :new.isbn := concat (:new.isbn, mod ((10 - mod ((to_number(substr (:new.isbn, 1, 1)) + 3 * to_number(substr (:new.isbn, 2, 1)) + to_number(substr (:new.isbn, 3, 1)) + 3 * to_number(substr (:new.isbn, 4, 1)) + to_number( substr (:new.isbn, 5, 1)) + 3 * to_number( substr (:new.isbn, 6, 1)) + to_number(substr (:new.isbn, 7, 1)) + 3 * to_number( substr (:new.isbn, 8, 1)) + to_number( substr (:new.isbn, 9, 1)) + 3 * to_number( substr (:new.isbn, 10, 1)) + to_number(substr (:new.isbn, 11, 1)) + 3 * to_number( substr (:new.isbn, 12, 1))), 10)), 10));
  end if;
end;
/

文档中的

convert功能：http://docs.oracle.com/cd/B28359_01/server.111/b28286/functions027.htm#SQLRF00620
文档中的to_number函数：http://docs.oracle.com/cd/E11882_01/server.112/e41084/functions211.htm#SQLRF06140

PL / SQL：更改插入数据时触发错误

1 个答案: