如何基于行本身中的数量字段返回多个相同的行? [英] How can I return multiple identical rows based on a quantity field in the row itself?

问题描述

我正在使用oracle从购物应用中输出订单项.每个项目的数量字段都可能大于1，如果是，我想将该行返回N次.

I'm using oracle to output line items in from a shopping app. Each item has a quantity field that may be greater than 1 and if it is, I'd like to return that row N times.

这就是我要谈论的桌子

product_id, quanity
1, 3,
2, 5

我正在寻找一个会返回的查询

And I'm looking a query that would return

1,3
1,3
1,3
2,5
2,5
2,5
2,5
2,5

这可能吗?我看到了SQL Server 2005的此答案，我正在寻找在oracle中几乎是完全一样的东西.不幸的是，建立专用号码表不是一种选择.

Is this possible? I saw this answer for SQL Server 2005 and I'm looking for almost the exact thing in oracle. Building a dedicated numbers table is unfortunately not an option.

推荐答案

在此示例中，我最多使用15，但是您应该将其设置为9999或将支持的最大数量.

I've used 15 as a maximum for the example, but you should set it to 9999 or whatever the maximum quantity you will support.

create table t (product_id number, quantity number);
insert into t values (1,3);
insert into t values (2,5);

select t.* 
  from t 
    join (select rownum rn from dual connect by level < 15) a 
                                 on a.rn <= t.quantity
order by 1;

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