我有两张桌子:
product (idproduct, name, description, tax)
product_storage (idstorage, idproduct, added, quantity, price)
对于每种产品,它可能是不同的价格,而最老的是“先卖”
例如在存储中我有:
1, 1, 2010-01-01, 0, 10.0
2, 1, 2010-01-02, 0, 11.0
3, 1, 2010-01-03, 10, 12.0
4, 2, 2010-01-04, 0, 12.0
5, 2, 2010-01-05, 10, 11.0
6, 2, 2010-01-06, 10, 13.0
7, 3, 2010-01-07, 10, 14.0
8, 3, 2010-01-08, 10, 16.0
9, 3, 2010-01-09, 10, 13.0
现在我需要选择当前价格的所有产品,这是product_storage中最旧的一行,其中数量为>每种产品0:
SELECT p.idproduct, p.name, p.tax,
(SELECT s.price
FROM product_storage s
WHERE s.idproduct=p.idproduct AND s.quantity > 0
ORDER BY s.added ASC
LIMIT 1) AS price
FROM product p;
工作正常,但当我想在查询中计算含税价格时,它不会起作用:
SELECT p.idproduct, p.name, p.tax,
(SELECT s.price
FROM product_storage s
WHERE s.idproduct=p.idproduct AND s.quantity > 0
ORDER BY s.added ASC
LIMIT 1) AS price,
(price * (1 + tax/100)) AS price_with_tax
FROM product p;
MySQL说:
Unknown column 'price' in 'field list'
更新
使用子查询作为表几乎解决问题(查看答案) - 现在唯一的问题是如何从product_storage中为多个外键选择最旧的行(每个idproduct只有一个)。
更新2
感谢cmptrgeekken提供了很好的解决方案:))
答案 0 :(得分:2)
使用子查询作为表格可能会更好:
SELECT p.idproduct, p.name, p.tax, s.price, (s.price * (1 + p.tax/100)) as price_with_tax
FROM product p
INNER JOIN (SELECT idproduct, price
FROM product_storage
WHERE quantity > 0) s
ON p.idproduct = s.idproduct
INNER JOIN (SELECT idproduct, MIN(added) min
FROM product_storage
GROUP BY idproduct) f
ON s.idproduct = f.idproduct AND s.added = f.min
编辑:已更新,因为税收在另一个表格中,因此我必须移动该计算的位置。
编辑2:好的,再次改变一下,试图正确过滤product_storage表。
答案 1 :(得分:1)
这几乎没问题:
SELECT p.idproduct, p.name, p.tax,
sub.price, (sub.price * (1+tax/100)) as price_with_tax
FROM product p,
(SELECT s.idproduct, s.price
FROM product_storage s
WHERE quantity > 0
ORDER BY added ASC) sub
WHERE p.idproduct=sub.idproduct
但是每个产品都会返回product_storage中的所有行:/
答案 2 :(得分:1)
您收到price doesn't exist
错误的原因是您无法在列列表中引用别名列。要解决此问题,请将price
值存储在用户定义的变量中并引用它,如下所示:
SELECT p.idproduct, p.name, p.tax,
@price := (SELECT s.price
FROM product_storage s
WHERE s.idproduct=p.idproduct AND s.quantity > 0
ORDER BY s.added ASC
LIMIT 1) AS price,
(@price * (1 + tax/100)) AS price_with_tax
FROM product p;
答案 3 :(得分:0)
就MySQL而言,最后出现的“价格”一词是指产品p中的一个字段,因此是错误。您需要再次引用上面的别名子查询:
SELECT p.idproduct, p.name, p.tax,
(SELECT s.price
FROM product_storage s
WHERE s.idproduct=p.idproduct AND s.quantity > 0
ORDER BY s.added ASC
LIMIT 1) AS price,
( (SELECT s.price
FROM product_storage s
WHERE s.idproduct=p.idproduct AND s.quantity > 0
ORDER BY s.added ASC
LIMIT 1) * (1 + tax/100)) AS price_with_tax
FROM product p;
答案 4 :(得分:0)
首先,您希望获得产品的最低存储ID。
SELECT idproduct, MIN(idstorage) idstorage FROM product_storage
WHERE quantity>0 AND idproduct IN (#, #, ...)
GROUP BY idstorage
idstorage,idproduct,添加,数量,价格 然后,您可以使用最小存储ID加入该查询和product_storage表(再次),以使用正确的定价信息获取您的产品信息。
SELECT idproduct, name, description, tax, ps.price, ps.quantity,
FROM product AS p
JOIN
(SELECT idproduct, MIN(idstorage) idstorage FROM product_storage
WHERE quantity>0 AND idproduct IN (#, #, ...)
GROUP BY idstorage) AS min_id
ON p.idproduct=min_id.idproduct
RIGHT JOIN product_storage AS ps ON ps.idstorage=min_id.idstorage
WHERE idproduct IN (#, #, ...)