mysql - 如何检索组的所有属性并获取与组关联的给定产品的属性值

Posted 2023-03-29

【中文标题】mysql - 如何检索组的所有属性并获取与组关联的给定产品的属性值

【英文标题】：mysql - How to retrieve all the attributes of the group and to take attribute values for a given product that is associated with the group

【发布时间】：2014-02-16 18:30:18

【问题描述】：

如何检索组的所有属性，例如。 WHERE idGroup = '2' AND idLanguage = '1' 然后为某些 product WHERE 获取 attrValue if exists。组='2'； 如果不存在打印 attrValue = ''

---

例如

我的桌子

表格：产品

idProduct idGroup

表格：products_attributes

idProduct idAttr idLanguage 属性值

表格：属性

idAttr nameAttr idLanguage

表：groups_attributes

idGroup idAttr

---

用这个查询

SELECT a.idAttr, a.nameAttr
FROM attributes  AS a
INNER JOIN groups_attributes AS ga ON a.idAttr= ga.idAttr
WHERE ga.idGroup = 1 AND ga.idLanguage = eng

结果是

Array
(
    [0] => Array (
            [idAttr] => 1
            [idGroup] => 1
            [nameAttr] => color
        )
    [1] => Array (
            [idAttr] => 2
            [idGroup] => 1
            [nameAttr] => height
        )
    [2] => Array (
            [idAttr] => 3
            [idGroup] => 1
            [nameAttr] => width
        )
)       

如何加入表products_attributes得到这样的结果？？

Array
(
    [0] => Array (
            [idAttr] => 1
            [idGroup] => 1
            [nameAttr] => color
            [idProduct] => 1
            [valueAttr] => NULL or ''
        )
    [1] => Array (
            [idAttr] => 2
            [idGroup] => 1
            [nameAttr] => height
            [idProduct] => 1
            [valueAttr] => 1600
        )
    [2] => Array (
            [idAttr] => 3
            [idGroup] => 1
            [nameAttr] => width
            [idProduct] => 1
            [valueAttr] => 900
        )
)       

我仅在设置属性值时才保存产品的属性（在此例如，未为产品 idProduct=1 设置属性 color）

在编辑产品数据时，如何检索组的所有属性并获取与组关联的给定产品的属性值？

【参考方案1】：

尝试使用左外连接和 case 语句，如下所示（您必须确保表之间的连接条件正确）。我没有在连接中包含产品表，但是如果你也想加入产品，你也离开了外部加入它。

SELECT a.idAttr, a.nameAttr, case when pa.idProduct is not null then pa.attrValue else "" end
FROM attributes  AS a
INNER JOIN groups_attributes AS ga ON a.idAttr= ga.idAttr
LEFT OUTER JOIN products_attributes AS pa ON a.idAttr=pa.idAttr
WHERE ga.idGroup = 1 AND ga.idLanguage = eng

【参考方案2】：

这是加入产品的查询，如果您想要 '' 而不是 null，请使用 coalesce(pa.attrValue, '') as attrValue 代替 pa.attrValue

SELECT a.idAttr, ga.idGroup, a.nameAttr, p.idProduct, pa.attrValue
FROM attributes  AS a
INNER JOIN groups_attributes AS ga ON a.idAttr= ga.idAttr
INNER JOIN products AS p ON ga.idGroup = p.idGroup
LEFT JOIN products_attributes pa ON p.idProduct = pa.idProduct AND pa.idAttr = a.idAttr and pa.idLanguage = ga.idLanguage 
WHERE ga.idGroup = 1 AND ga.idLanguage = eng