我的带有光标的购物车程序正在抛出错误

Posted 2021-04-09

我有一个团队项目，我们正在创建一个购物车应用程序。我得到了一些反馈并修复了它，把它变成了一个带光标的程序。但是，我们仍然会收到我不知道如何解决的错误，例如尝试将null值放入不能为null的表列中。我不知道为什么它认为我试图输入一个空值。我们的项目明天到期，所以请帮忙！

我一开始尝试将其作为触发器，但它没有工作，因此建议将其转换为带光标的过程，所以我这样做了。

create or replace PROCEDURE CANCELCART (arg_cart_id IN number)

IS
ws_prod_id number;
ws_item_quantity_in_cart number;
ws_cart_id number;
ws_cart_status char;

cursor cancel IS
select item_product_id, item_quantity_in_cart
FROM sc_items i
WHERE item_cart_id = arg_cart_id
group by item_product_id;

alreadycancelled exception;

BEGIN
select max(cart_id) into ws_cart_id
from sc_cart
where arg_cart_id = cart_id;

/*cart check*/
select max(cart_status) into ws_cart_status
from sc_cart
where arg_cart_id = cart_id;

if ws_cart_id is null
    then raise alreadycancelled;
    end if;

open cancel;
LOOP
fetch cancel into ws_prod_id, ws_item_quantity_in_cart;
    UPDATE sc_product p SET prod_quan_avail = prod_quan_avail + ws_quantity_in_cart, 
    prod_quan_sold = prod_quan_sold - ws_quantity_in_cart
    WHERE prod_id = ws_prod_id;
    DELETE FROM sc_items i WHERE i.item_cart_id = arg_cart_id;
END LOOP;
close cancel;

DELETE FROM sc_cart c WHERE c.cart_id = arg_cart_id;

EXCEPTION
when alreadycancelled 
    then raise_application_error(-20400, 'Cart does not exist');

END;

我需要此代码取消购物车并将所有商品数量退回原始库存。

答案

除了使用数据类型定义ws_quantity_in_cart变量之外，您的代码块没有太多遗漏部分，并且为已经包含的其他类型的异常添加更多处理（ORA-20400）

CREATE OR REPLACE PROCEDURE CANCELCART( arg_cart_id sc_cart.cart_id%type ) IS
    ws_prod_id               sc_product.prod_id%type;
    ws_item_quantity_in_cart sc_product.prod_quan_avail%type;
    ws_cart_id               sc_cart.cart_id%type;
    ws_cart_status           sc_cart.cart_status%type;
    ws_quantity_in_cart      sc_product.prod_quan_sold%type;

    cursor cancel IS
    select item_product_id, item_quantity_in_cart
      from sc_items i
     where item_cart_id = arg_cart_id
     group by item_product_id;

    alreadycancelled exception;

BEGIN
    select max(cart_id)
      into ws_cart_id
      from sc_cart
     where arg_cart_id = cart_id;

    /*cart check*/
    select max(cart_status)
      into ws_cart_status
      from sc_cart
     where arg_cart_id = cart_id;

    if ws_cart_id is null
        then raise alreadycancelled;
        end if;

    open cancel;
    loop
    fetch cancel into ws_prod_id, ws_item_quantity_in_cart;
        update sc_product p 
           set prod_quan_avail = prod_quan_avail + ws_quantity_in_cart,
               prod_quan_sold = prod_quan_sold - ws_quantity_in_cart
         where prod_id = ws_prod_id;
        delete sc_items i where i.item_cart_id = arg_cart_id;
    end loop;
    close cancel;

    delete sc_cart c where c.cart_id = arg_cart_id;

 exception when alreadycancelled  then raise_application_error(-20400, 'Cart does not exist');
           when      others       then raise_application_error(SQLCODE,SQLERRM);

END;

首选使用<table_name>.<column_name>.%type的列原始数据类型来定义变量的数据类型，而不使用char类型的固定长度字符串类型变量，而是使用varchar2。