mysql如果不等于0，则从列中选择，否则从另一列中选择

我有这个疑问

            SELECT 
                products.*, colors.name AS colorName, makes.name AS makeName, genders.name AS genderName,
                GROUP_CONCAT(DISTINCT categories.name ORDER BY categories.name) AS distCategories, 
                GROUP_CONCAT(DISTINCT subcategories.name ORDER BY subcategories.name) AS distSubcategories, 
                GROUP_CONCAT(DISTINCT makes.name ORDER BY makes.name) AS distMakes, 
                GROUP_CONCAT(DISTINCT products_availability.size ORDER BY products_availability.size) AS distSizes 
            FROM products 
                LEFT JOIN colors ON products.color = colors.id 
                LEFT JOIN makes ON products.make = makes.id 
                LEFT JOIN genders ON products.gender = genders.id 
                LEFT JOIN products_and_categories ON products_and_categories.product = products.id 
                LEFT JOIN products_and_subcategories ON products_and_subcategories.product = products.id 
                LEFT JOIN products_availability ON products_availability.product = products.id 
                LEFT JOIN categories ON products_and_categories.category = categories.id 
                LEFT JOIN subcategories ON products_and_subcategories.subcategory = subcategories.id 
            WHERE products.gender IN(5, 6, 7) AND products.type = 5 AND $where 
            GROUP BY(products.id)
            ORDER BY products.id ASC

我希望能够根据价格选择一些产品

---

如果列

sale\u price

不是0，那么我想说

WHERE sale\u price，在您的案例陈述中稍加修改，我想您可以让它工作。尝试以下方法：

SELECT 
products.*, 
colors.name AS colorName, 
makes.name AS makeName,  
genders.name AS genderName,
GROUP_CONCAT(DISTINCT categories.name ORDER BY categories.name) AS distCategories, 
GROUP_CONCAT(DISTINCT subcategories.name ORDER BY subcategories.name) AS distSubcategories, 
GROUP_CONCAT(DISTINCT makes.name ORDER BY makes.name) AS distMakes, 
GROUP_CONCAT(DISTINCT products_availability.size ORDER BY products_availability.size) AS distSizes 
FROM products 
LEFT JOIN colors ON products.color = colors.id 
LEFT JOIN makes ON products.make = makes.id 
LEFT JOIN genders ON products.gender = genders.id 
LEFT JOIN products_and_categories ON products_and_categories.product = products.id 
LEFT JOIN products_and_subcategories ON products_and_subcategories.product = products.id 
LEFT JOIN products_availability ON products_availability.product = products.id 
LEFT JOIN categories ON products_and_categories.category = categories.id 
LEFT JOIN subcategories ON products_and_subcategories.subcategory = subcategories.id 
WHERE products.sale_price = CASE WHEN products.sale_price > 0 
THEN products.sale_price <=  value ELSE products.price <=  value END
AND products.gender IN(5, 6, 7) 
AND products.type = 5 
GROUP BY(products.id)
ORDER BY products.id ASC;

选择
产品。*，
colors.name作为colorName，
make.name作为makeName，
genders.name作为genderName，
将组_CONCAT（不同类别。名称按类别排序。名称）作为distCategories，
将组_CONCAT（不同的子类别。名称按子类别排序。名称）作为distSubcategories，
组_CONCAT（按makes.name的不同makes.name顺序）作为distmake，
按产品分组（不同产品的可用性。按产品的订单大小。\u可用性。大小）作为DistSize
来自产品
产品上的左连接颜色。颜色=颜色。id
products.make=makes.id上的左连接makes
左键连接products.gender=genders.id上的genders
左键连接products_和_categories.product=products.id上的products_和_类别
左键连接产品和子类别上的产品和子类别。产品=产品。id
左连接产品\u产品上的可用性\u可用性.product=products.id
左连接产品上的类别和类别。类别=类别。id
左连接产品和子类别上的子类别。子类别=子类别。id
其中products.sale\u price=products.sale\u price>0时的情况
那么products.sale\u price谢谢您的回复，不幸的是，我在ELSE products.price附近发现了语法错误。这里的一些逻辑看起来是错误的。在WHERE子句中，您试图将一些值分配给两个不同的变量。我们不能将CASE放在SELECT本身中，并保持WHERE子句不受它影响吗？我不需要使用
CASE
，它只是我在搜索这个特定问题时发现的一种方法。最后我想我明白了，现在关于价格的
WHERE
是这样的
WHERE（（products.sale\u price 0）或products.price耶..这看起来是一个更简单的解决方案：）
SELECT 
products.*, 
colors.name AS colorName, 
makes.name AS makeName,  
genders.name AS genderName,
GROUP_CONCAT(DISTINCT categories.name ORDER BY categories.name) AS distCategories, 
GROUP_CONCAT(DISTINCT subcategories.name ORDER BY subcategories.name) AS distSubcategories, 
GROUP_CONCAT(DISTINCT makes.name ORDER BY makes.name) AS distMakes, 
GROUP_CONCAT(DISTINCT products_availability.size ORDER BY products_availability.size) AS distSizes 
FROM products 
LEFT JOIN colors ON products.color = colors.id 
LEFT JOIN makes ON products.make = makes.id 
LEFT JOIN genders ON products.gender = genders.id 
LEFT JOIN products_and_categories ON products_and_categories.product = products.id 
LEFT JOIN products_and_subcategories ON products_and_subcategories.product = products.id 
LEFT JOIN products_availability ON products_availability.product = products.id 
LEFT JOIN categories ON products_and_categories.category = categories.id 
LEFT JOIN subcategories ON products_and_subcategories.subcategory = subcategories.id 
WHERE products.sale_price = CASE WHEN products.sale_price > 0 
THEN products.sale_price <=  value ELSE products.price <=  value END
AND products.gender IN(5, 6, 7) 
AND products.type = 5 
GROUP BY(products.id)
ORDER BY products.id ASC;