我试图在我的 sql 查询中执行几个 JOINS,但遇到了问题。我需要做的是从poker_sites
中选择所有字段然后从 networks
中获取 2 个相关字段如果可用,请从 editor_content
获取平均评级
我遇到的问题是查询只返回一行,而实际上应该至少有三行。
任何帮助将不胜感激。
这是我的 SQL
SELECT AVG(editor_content.rating) AS rating, poker_sites.*,
networks.network_name, networks.network_icon FROM poker_sites
LEFT JOIN networks
ON (poker_sites.network_id=networks.network_id)
LEFT JOIN editor_content
ON (poker_sites.site_id=editor_content.assign_id)
WHERE poker_sites.published=1
最佳答案
如果您想使用聚合函数(在本例中为 AVG)获取多个结果,则需要 GROUP BY。
SELECT x.avgRating AS rating, poker_sites.*,
networks.network_name, networks.network_icon
FROM poker_sites
LEFT JOIN networks
ON (poker_sites.network_id=networks.network_id)
LEFT JOIN
(
SELECT AVG(editor_content.rating) as avgRating, editor_content.assign_id
FROM editor_content
GROUP BY editor_content.assign_id
) x
ON (poker_sites.site_id = x.assign_id)
WHERE poker_sites.published=1
关于SQL JOIN 多个表并获取 AVG,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/12433749/