mysql-如何检索组的所有属性，以及获取与组关联的给定产品的属性值

如何检索组的所有属性，例如，其中idGroup='2'和idLanguage='1'
然后对一些产品获取attrValue（如果存在），例如group='2'如果不存在，打印属性值

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e、 g

我的桌子 表格：产品

• idProduct
• idGroup

表格：产品属性

• idProduct
• idAttr
• 闲置语言
• 属性值

表格：属性

• idAttr
• 名称属性
• 闲置语言

表格：组属性

• idGroup
• idAttr

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有了这个疑问

结果是

如何连接表产品属性以获得这样的结果

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保存产品属性（例如，未为产品设置属性

color

）

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编辑产品数据时，如何检索组的所有属性并获取属性值​​对于与组关联的给定产品？

请尝试使用下面的左外部联接和case语句（您必须确保表之间的联接条件正确）。我没有将products表包括在join中，但是如果您也想加入products，那么您也可以将outer join保留在其中

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

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这是已加入产品的查询，如果希望“”而不是null，请使用

coalesce（pa.attrValue，'）作为attrValue

而不是

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

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

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