[英]What type of JOIN to use? mysql
我有一个查询,其中选择了所有出售的产品。 我想做的是反向查询,并在一段时间内获得所有未售出的产品。
这是对一段时间内售出的所有产品的查询。
SELECT
product.product_id,
product.product_brand_id,
product.product_model_id,
product.product_subcategory_id,
product.product_retail_price,
product.product_wholesale_price,
product.product_aretail_price,
product.product_awholesale_price,
product.product_oretail_price,
product.product_owholesale_price,
product.product_quoted_price,
product.product_aquoted_price,
product.product_dquoted_price,
product_sold.product_type, SUM(product_sold.product_quantity) AS product_quantity_sold, SUM(product_sold.product_total_price) AS total_price_sold
FROM product
INNER JOIN product_sold
ON product.product_id = product_sold.product_id
AND product.product_subcategory_id = '$subcategory_id'
INNER JOIN sales
ON sales.sales_id = product_sold.product_sales_id
WHERE sales.sales_approved = '1'
AND sales.sales_approved_time > '$start_timestamp'
AND sales.sales_approved_time < '$end_timestamp'
GROUP BY product_sold.product_type, product.product_id
ORDER BY SUM(product_sold.product_quantity) DESC
有人可以指导我如何获得未售出的产品吗,我的库存有点不知所措。 谢谢。
回答:
SELECT
p.product_id,
p.product_brand_id,
p.product_model_id,
p.product_subcategory_id,
p.product_retail_price,
p.product_wholesale_price,
p.product_aretail_price,
p.product_awholesale_price,
p.product_oretail_price,
p.product_owholesale_price,
p.product_quoted_price,
p.product_aquoted_price,
p.product_dquoted_price,
pq.product_stock_type
FROM
product p
LEFT JOIN
product_sold ps
ON
p.product_id = ps.product_id
INNER JOIN
product_stock pq
ON
p.product_id = pq.product_id
AND
pq.product_quantity > 0
WHERE
p.product_subcategory_id = '$subcategory_id'
AND
ps.product_id IS NULL
通常,获取不包含在集合B中的集合A成员的方法是使用左连接。 我将从简化您的查询开始:
SELECT p.product_id, ps.product_id from product p
LEFT JOIN product_sold ps
WHERE ps.product_id IS NULL
这将返回在product_sold中没有值的所有产品记录。 您应该可以从那里添加细节。
尝试这个 :
SELECT
product.product_id
FROM product
LEFT JOIN
(
SELECT
product.product_id
FROM product
INNER JOIN product_sold
ON product.product_id = product_sold.product_id
AND product.product_subcategory_id = '$subcategory_id'
INNER JOIN sales
ON sales.sales_id = product_sold.product_sales_id
WHERE sales.sales_approved = '1'
AND sales.sales_approved_time > '$start_timestamp'
AND sales.sales_approved_time < '$end_timestamp'
GROUP BY product_sold.product_type, product.product_id
) AS psold
ON product.product_id = psold.product_id
WHERE psold.product_id IS NULL
这样,您有一个出售产品的子请求,并且将其与所有产品结合在一起,WHERE子句仅选择第一个表中的产品(所有产品),而不选择第二个表中的产品(已售产品)。
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