將1個表中的3行聯接到另一個表中的1行

Question

我需要創建一個記錄集，該記錄集將一個表的3行連接到另一表的1行。

目前我有：

   SELECT * 
     FROM tb_product_sub_cat 
LEFT JOIN tb_products ON tb_product_sub_cat.category_id = tb_products.product_subcategory 
    WHERE tb_product_sub_cat.category_name = %s 

我也需要：

tb_product_sub_cat.category_id = tb_products.product_subcategory2 AND
tb_product_sub_cat.category_id = tb_products.product_subcategory3

我需要查找所有/或所有產品類別中都包含“填充物”的所有產品。

Answer 1

SELECT * FROM tb_product_sub_cat 
INNER JOIN tb_products 
ON tb_product_sub_cat.category_id =   tb_products.product_subcategory2 
AND tb_product_sub_cat.category_id = tb_products.product_subcategory3 
AND   tb_product_sub_cat.category_id =  tb_products.product_subcategory  
WHERE tb_product_sub_cat.category_name = %s 

這是我對您的情況的解釋。 讓我知道這是否適合您或您需要詳細說明。

編輯

SELECT * FROM tb_product_sub_cat 
LEFT JOIN tb_products 
ON tb_product_sub_cat.category_id =   tb_products.product_subcategory2 
AND tb_product_sub_cat.category_id = tb_products.product_subcategory3 
AND   tb_product_sub_cat.category_id =  tb_products.product_subcategory  
WHERE tb_product_sub_cat.category_name = %s

Answer 2

不清楚您想聽什么，但這看起來像是UNION的工作：-

    SELECT * FROM tb_product_sub_cat LEFT JOIN tb_products ON tb_product_sub_cat.category_id = tb_products.product_subcategory WHERE tb_product_sub_cat.category_name = %s 
UNION
SELECT * FROM tb_product_sub_cat LEFT JOIN tb_products ON tb_product_sub_cat.category_id = tb_products.product_subcategory2 WHERE tb_product_sub_cat.category_name = %s
UNION
SELECT * FROM tb_product_sub_cat LEFT JOIN tb_products ON tb_product_sub_cat.category_id = tb_products.product_subcategory3 WHERE tb_product_sub_cat.category_name = %s

Answer 3

表別名將使您的生活更輕松：

   SELECT * 
     FROM tb_product_sub_cat t
LEFT JOIN tb_products tp ON t.category_id IN (tp.product_subcategory, tp.product_subcategory2, tp.product_subcategory3)
    WHERE t.category_name = %s