表:
Article | Quantity | pricePerUnit | order_id | article_id
--------|----------|--------------------------------------
14 | 2 | 10.0 | 1 | 1
X1 | 1 | 5.0 | 1 | 2
预期输出:
Article | Quantity | pricePerUnit | order_id
--------|----------|------------------------
14 | 1 | 10.0 | 1
14 | 1 | 10.0 | 1
X1 | 1 | 5.0 | 1
什么是快速 SELECT 来为每篇文章的每个数量填充 1 行结果集?
抱歉,我没有尝试任何事情,我不确定这是否可行。自加入..不会有帮助,分组功能,..
也许按 order_id、article_id、数量分组
不知何故..
最佳答案
更新:对于三个的最大数量,只需这样做
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
这里是SQLFiddle 演示
<小时/>原答案:你可以尝试
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最多取消为 100。如果您需要更多,请相应地进行更新。
这里是SQLFiddle 演示
<小时/>鉴于它是用于报告的,并且您有创建新表的必要权利,因此最好用可以以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;
然后你的查询将如下所示
SELECT Article, 1 Quantity, pricePerUnit, order_id
FROM articles a JOIN tally n
ON n.n <= a.Quantity
ORDER BY order_id, Article
这里是SQLFiddle 演示
关于mysql - 为每个 'quantity' 选择一行,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/24263054/