Question

表：

Article | Quantity | pricePerUnit | order_id | article_id
--------|----------|--------------------------------------
     14 |        2 |        10.0  |        1 |    1
     X1 |        1 |         5.0  |        1 |    2

预期产出：

Article | Quantity | pricePerUnit | order_id
--------|----------|------------------------
     14 |        1 |        10.0  |     1
     14 |        1 |        10.0  |     1
     X1 |        1 |         5.0  |     1

对于每篇文章的每个数量，使用1行填充结果集的快速SELECT是什么？

抱歉，我没有尝试任何事情，我不确定这是否可行。自我加入..不会是一个帮助，分组功能，..

也许GROUP BY order_id, article_id, quantity以某种方式......

Answer 1

更新：对于三的最大数量，只需执行

SELECT Article, 1 Quantity, pricePerUnit, order_id
  FROM articles a JOIN 
(
   SELECT 1 AS n UNION ALL 
   SELECT 2 UNION ALL 
   SELECT 3
) n
    ON n.n <= a.Quantity
 ORDER BY order_id, Article

这是 SQLFiddle 演示

原始回答：您可以尝试

SELECT Article, 1 Quantity, pricePerUnit, order_id
  FROM articles a JOIN 
(
   SELECT a.N + b.N * 10 + 1 n
     FROM 
    (SELECT 0 AS N UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) a
   ,(SELECT 0 AS N UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) b
) n
    ON n.n <= a.Quantity
 ORDER BY order_id, Article

内部选择返回100行，这意味着您可以将数量取消转换为值100.如果您需要更多，请相应更新。

这是 SQLFiddle 演示

鉴于它是一个报告，你有权创建一个新表，最好用一个你可以用相同方式创建的计数（数字）表替换内部选择：

CREATE TABLE tally (n int not null auto_increment primary key);
INSERT INTO tally
SELECT a.N + b.N * 10 + 1 n
  FROM 
(SELECT 0 AS N UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) a
,(SELECT 0 AS N UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) b
ORDER BY n;

然后您的查询将显示为

SELECT Article, 1 Quantity, pricePerUnit, order_id
  FROM articles a JOIN tally n
    ON n.n <= a.Quantity
 ORDER BY order_id, Article

这是 SQLFiddle 演示

为每个“数量”选择一行＆＃39;

1 个答案: