在一個查詢中嵌套集合，產品數量和類別深度

Question

按照article的說明，我想獲得一個完整的樹，每個類別的深度都能正常工作。

我也想獲得每個類別的產品數量。我嘗試添加另一個COUNT（products_categories.product_id），但它與深度值混淆了。如何修改查詢以獲得每個類別的產品數量和深度？

products_categories 
---------------------- 
category_id 
product_id 


SELECT node.name, (COUNT(parent.name) - 1) AS depth 
FROM nested_category AS node, 
    nested_category AS parent 
WHERE node.lft BETWEEN parent.lft AND parent.rgt 
GROUP BY node.name 
ORDER BY node.lft 

換句話說，我想結合這兩個查詢。

SELECT node.name, (COUNT(parent.name) - 1) AS depth 
FROM nested_category AS node, 
    nested_category AS parent 
WHERE node.lft BETWEEN parent.lft AND parent.rgt 
GROUP BY node.name 
ORDER BY node.lft 

SELECT parent.name, COUNT(product.name) 
FROM nested_category AS node , 
    nested_category AS parent, 
    product 
WHERE node.lft BETWEEN parent.lft AND parent.rgt 
    AND node.category_id = product.category_id 
GROUP BY parent.name 
ORDER BY node.lft; 

Answer 1

我終於解決了我的問題。我將上述查詢結合起來，以便我可以像這樣獲得深度和產品數量。

SELECT parent.id, 
        parent.lft, 
        parent.rgt, 
        (SELECT COUNT(parent2.id) FROM businesscategories AS parent2 WHERE parent.lft > parent2.lft AND parent.rgt < parent2.rgt) AS depth, 
        COUNT(b_c.business_id) AS bcount 

       FROM businesscategories AS node, 
       businesscategories AS parent, 
       businesses_categories AS b_c, 
       WHERE node.lft BETWEEN parent.lft AND parent.rgt AND node.id = b_c.category_id 
       GROUP BY parent.id having depth > 0 
       ORDER BY parent.lft