每个产品需要 MySQL JOIN 到 return 产品所属的所有类别,即使只搜索一个类别也是如此
Need a MySQL JOIN to return all categories a product is in, per product, even if only one category is searched for
我定义了下表:
CREATE TABLE products (
product_id INTEGER(11) NOT NULL AUTO_INCREMENT,
name VARCHAR(255) NOT NULL,
section VARCHAR(255) DEFAULT NULL,
PRIMARY KEY (product_id)
) ENGINE=MyISAM;
CREATE TABLE categories (
category_id INTEGER(11) NOT NULL AUTO_INCREMENT,
name VARCHAR(255) NOT NULL,
PRIMARY KEY (category_id)
) ENGINE=MyISAM;
CREATE TABLE product_categories (
product_id INTEGER(11) NOT NULL,
category_id INTEGER(11) NOT NULL,
PRIMARY KEY (product_id, category_id)
) ENGINE=MyISAM;
实际上还有更多,这是优化更大、更复杂查询的一部分。其中一部分是将一些缓慢的子查询移动到视图中,到目前为止这有很大帮助。
当我添加 categories/product_categories 表并在允许用户按 products.section 或 categories.category_id 搜索时加入它们时,查询变得非常慢。 UI 将它们作为搜索参数传递进来,我试图为每个产品获取一行,其中包含其 ID、名称、部分以及与其关联的以逗号分隔的类别名称列表。我能够通过以下视图和查询更快地完成此操作:
CREATE OR REPLACE
ALGORITHM = MERGE
VIEW view_products_with_categories
AS
SELECT
p.product_id,
p.name,
p.section,
pc.name AS category
products p
LEFT JOIN product_categories pc on p.product_id = pc.product_id
LEFT JOIN categories c ON pc.category_id = c.category_id;
SELECT
product_id,
name,
section,
GROUP_CONCAT(DISTINCT category ORDER BY category) AS categories
FROM view_products_with_categories
GROUP BY product_id;
假设我们有以下行:
product_id name section category_id category
332913 Model Train Engine child-and-baby 1160 child-and-baby>baby-and-pre-schooltoys>playsets
332913 Model Train Engine child-and-baby 1308 toys>baby-and-preschool>playsets
332913 Model Train Engine child-and-baby 1312 toys>carstrains-and-planes>cars-and-vehicles
上面的简单查询给出了以下信息:
product_id name section categories
332913 Model Train Engine child-and-baby child-and-baby>baby-and-pre-schooltoys>playsets,toys>baby-and-preschool>playsets,toys>carstrains-and-planes>cars-and-vehicles
很好,符合预期。但是,我希望用户能够按 category_id 进行搜索。目前,我们的 UI 对类别名称做了一些自动完成魔术,并向动态生成的 SQL 添加了一个过滤器,其中包含 category_id。如果我在 GROUP_CONCAT 查询中留下 category_id,它会是 1160。假设他们想搜索第二个 (1308),所以我们修改查询如下:
SELECT
product_id,
name,
section,
GROUP_CONCAT(DISTINCT category ORDER BY category) AS categories
FROM view_products_with_categories
WHERE category_id = 1308
GROUP BY product_id;
现在我们得到以下信息:
product_id name section categories
332913 Model Train Engine child-and-baby toys>baby-and-preschool>playsets
再一次,正是您所期望的。但是,客户希望查看与具有他们正在搜索的一个或多个类别的产品关联的所有类别。因此,让我们制作一些简化的示例数据来向您展示我正在寻找的内容:
product_id name section category_id category
1 product_1 section_1 1 category_1
1 product_1 section_1 2 category_2
1 product_1 section_1 3 category_3
2 product_2 section_2 3 category_3
2 product_2 section_2 4 category_4
2 product_2 section_2 5 category_5
如果用户搜索 category_id = 3,我希望他们得到以下内容:
product_id name section categories
1 product_1 section_1 category_1, category_2, category_3
2 product_2 section_2 category_3, category_4, category_5
但我目前只得到:
product_id name section categories
1 product_1 section_1 category_3
2 product_2 section_2 category_3
我只是想不出没有子查询的方法,它的缓慢是我首先转向视图的原因。我希望我遗漏了一些非常明显的东西,可能是由于睡眠不足,所以我们将不胜感激。
更新:我还应该提到,产品可能不属于任何类别,因此我的代码中有 LEFT JOIN。
以下查询有效:(虽然我没有使用视图)
select pc1.product_id, products.name, products.section,
group_concat(categories.name)
from products
inner join product_categories pc1
on (pc1.product_id = products.product_id and pc1.category_id = 3)
inner join product_categories pc2
on (pc2.product_id = products.product_id)
inner join categories
on (categories.category_id = pc2.category_id)
group by pc1.product_id, products.name, products.section
如果您想使用视图,可以使用以下方法:
SELECT vpc.product_id,vpc.name,vpc.section,
GROUP_CONCAT(DISTINCT category ORDER BY category) AS categories
FROM view_products_with_categories vpc
inner join product_categories pc
on (pc.product_id = vpc.product_id and pc.category_id=3)
GROUP BY vpc.product_id, vpc.name, vpc.section;
我定义了下表:
CREATE TABLE products (
product_id INTEGER(11) NOT NULL AUTO_INCREMENT,
name VARCHAR(255) NOT NULL,
section VARCHAR(255) DEFAULT NULL,
PRIMARY KEY (product_id)
) ENGINE=MyISAM;
CREATE TABLE categories (
category_id INTEGER(11) NOT NULL AUTO_INCREMENT,
name VARCHAR(255) NOT NULL,
PRIMARY KEY (category_id)
) ENGINE=MyISAM;
CREATE TABLE product_categories (
product_id INTEGER(11) NOT NULL,
category_id INTEGER(11) NOT NULL,
PRIMARY KEY (product_id, category_id)
) ENGINE=MyISAM;
实际上还有更多,这是优化更大、更复杂查询的一部分。其中一部分是将一些缓慢的子查询移动到视图中,到目前为止这有很大帮助。
当我添加 categories/product_categories 表并在允许用户按 products.section 或 categories.category_id 搜索时加入它们时,查询变得非常慢。 UI 将它们作为搜索参数传递进来,我试图为每个产品获取一行,其中包含其 ID、名称、部分以及与其关联的以逗号分隔的类别名称列表。我能够通过以下视图和查询更快地完成此操作:
CREATE OR REPLACE
ALGORITHM = MERGE
VIEW view_products_with_categories
AS
SELECT
p.product_id,
p.name,
p.section,
pc.name AS category
products p
LEFT JOIN product_categories pc on p.product_id = pc.product_id
LEFT JOIN categories c ON pc.category_id = c.category_id;
SELECT
product_id,
name,
section,
GROUP_CONCAT(DISTINCT category ORDER BY category) AS categories
FROM view_products_with_categories
GROUP BY product_id;
假设我们有以下行:
product_id name section category_id category
332913 Model Train Engine child-and-baby 1160 child-and-baby>baby-and-pre-schooltoys>playsets
332913 Model Train Engine child-and-baby 1308 toys>baby-and-preschool>playsets
332913 Model Train Engine child-and-baby 1312 toys>carstrains-and-planes>cars-and-vehicles
上面的简单查询给出了以下信息:
product_id name section categories
332913 Model Train Engine child-and-baby child-and-baby>baby-and-pre-schooltoys>playsets,toys>baby-and-preschool>playsets,toys>carstrains-and-planes>cars-and-vehicles
很好,符合预期。但是,我希望用户能够按 category_id 进行搜索。目前,我们的 UI 对类别名称做了一些自动完成魔术,并向动态生成的 SQL 添加了一个过滤器,其中包含 category_id。如果我在 GROUP_CONCAT 查询中留下 category_id,它会是 1160。假设他们想搜索第二个 (1308),所以我们修改查询如下:
SELECT
product_id,
name,
section,
GROUP_CONCAT(DISTINCT category ORDER BY category) AS categories
FROM view_products_with_categories
WHERE category_id = 1308
GROUP BY product_id;
现在我们得到以下信息:
product_id name section categories
332913 Model Train Engine child-and-baby toys>baby-and-preschool>playsets
再一次,正是您所期望的。但是,客户希望查看与具有他们正在搜索的一个或多个类别的产品关联的所有类别。因此,让我们制作一些简化的示例数据来向您展示我正在寻找的内容:
product_id name section category_id category
1 product_1 section_1 1 category_1
1 product_1 section_1 2 category_2
1 product_1 section_1 3 category_3
2 product_2 section_2 3 category_3
2 product_2 section_2 4 category_4
2 product_2 section_2 5 category_5
如果用户搜索 category_id = 3,我希望他们得到以下内容:
product_id name section categories
1 product_1 section_1 category_1, category_2, category_3
2 product_2 section_2 category_3, category_4, category_5
但我目前只得到:
product_id name section categories
1 product_1 section_1 category_3
2 product_2 section_2 category_3
我只是想不出没有子查询的方法,它的缓慢是我首先转向视图的原因。我希望我遗漏了一些非常明显的东西,可能是由于睡眠不足,所以我们将不胜感激。
更新:我还应该提到,产品可能不属于任何类别,因此我的代码中有 LEFT JOIN。
以下查询有效:(虽然我没有使用视图)
select pc1.product_id, products.name, products.section,
group_concat(categories.name)
from products
inner join product_categories pc1
on (pc1.product_id = products.product_id and pc1.category_id = 3)
inner join product_categories pc2
on (pc2.product_id = products.product_id)
inner join categories
on (categories.category_id = pc2.category_id)
group by pc1.product_id, products.name, products.section
如果您想使用视图,可以使用以下方法:
SELECT vpc.product_id,vpc.name,vpc.section,
GROUP_CONCAT(DISTINCT category ORDER BY category) AS categories
FROM view_products_with_categories vpc
inner join product_categories pc
on (pc.product_id = vpc.product_id and pc.category_id=3)
GROUP BY vpc.product_id, vpc.name, vpc.section;