我有一个MYSQL表,我想在其中获得带有产品ID计数的平均评分。这是表的示例。
╔════╦═══════════════╦══════════╦══════════╗
║ ID ║ product_Id ║ rating ║ status ║
╠════╬═══════════════╬══════════╬══════════╣
║ 1 ║ 5 ║ 1 ║ 1 ║
║ 2 ║ 5 ║ 3 ║ 1 ║
║ 3 ║ 5 ║ 4 ║ 1 ║
║ 4 ║ 4 ║ 3 ║ 1 ║
║ 5 ║ 4 ║ 5 ║ 1 ║
║ 6 ║ 6 ║ 4 ║ 1 ║
║ 7 ║ 6 ║ 4 ║ 1 ║
╚════╩═══════════════╩══════════╩══════════╝
我已经完成了这段代码,但是没有得到想要的结果。
SELECT r.product_id, ROUND(AVG(r.rating),0) as avg_rating, COUNT(r.product_id) AS products_total FROM review r
WHERE r.status = 1
GROUP BY r.product_id ASC
给我的结果是平均等级(同一产品ID的等级数)
我希望将结果打印为平均评分(具有相同评分的产品ID的数量)
如何获得以上结果
如果我理解的话,则需要两个级别的聚合:
SELECT avg_rating, COUNT(*)
FROM (SELECT r.product_id, AVG(r.rating) as avg_rating, COUNT(r.product_id) AS products_total
FROM review r
WHERE r.status = 1
GROUP BY r.product_id
) p
GROUP BY avg_rating