我有 1 个字符串类型的表。 (照片添加、照片评论等) 然后我还有另外 4 个与这些类型连接的表。
我需要进行一个查询,根据类型从所有这些表中选择数据。
我创建了这个,但它不起作用。
SELECT DISTINCT a.id, a.event, a.params, a.created_at, a.item_id, a.sender_id, a.receiver_id, u.name, u.id as userid
FROM `eva49_lovefactory_activity` a, eva49_users u
CASE a.event
WHEN "photo_add" THEN
INNER JOIN eva49_lovefactory_photos lp ON lp.id = a.item_id AND lp.fsk18 = -1
WHEN "group_create" THEN
INNER JOIN eva49_lovefactory_groups lg ON lg.id = a.item_id AND lg.fsk18 = -1
WHEN "photo_comment" THEN
INNER JOIN eva49_lovefactory_item_comments lic ON lic.item_id = a.item_id AND lic.fsk18 = -1
WHEN "profile_comment" THEN
INNER JOIN eva49_lovefactory_item_comments lic ON lic.item_id = a.item_id AND lic.fsk18 = -1
WHEN "profile_comment" THEN
INNER JOIN eva49_lovefactory_profiles lp ON lp.user_id = a.receiver_id AND lp.status_fsk18 = -1
ELSE 1=1
END
WHERE (u.id = a.sender_id OR u.id = a.receiver_id) and (u.id <> 379)
ORDER BY a.created_at DESC LIMIT 0, 10
有什么办法可以配对表格吗?数据库结构是这样给我的。
编辑:
有一个表“eva49_lovefactory_activity”,其中包含有关最近事件的信息。它有一个“事件”列,其中包含带有事件名称的字符串(photo_add、photo_comment 等)
还有其他表 - eva49_lovefactory_photos、eva49_lovefactory_profiles、eva49_lovefactory_groups 等。在这些表中,我必须查找该项目是否已获得管理员批准。如果是的话我可以展示一下。 (fsk18 = -1)
最佳答案
将 CASE 条件移至 JOIN 条件并执行 LEFT JOIN..
SELECT DISTINCT a.id, a.event, a.params, a.created_at, a.item_id, a.sender_id, a.receiver_id, u.name, u.id as userid
FROM `eva49_lovefactory_activity` a, eva49_users u
LEFT JOIN eva49_lovefactory_photos lp ON lp.id = a.item_id AND lp.fsk18 = -1
AND a.event='photo_add'
LEFT JOIN eva49_lovefactory_groups lg ON lg.id = a.item_id AND lg.fsk18 = -1
AND a.event='group_create'
LEFT JOIN eva49_lovefactory_item_comments lic ON lic.item_id = a.item_id AND
lic.fsk18 = -1 AND a.event='photo_comment'
LEFT JOIN eva49_lovefactory_item_comments lic ON lic.item_id = a.item_id AND
lic.fsk18 = -1 AND a.event='profile_comment'
WHERE (u.id = a.sender_id OR u.id = a.receiver_id) and (u.id <> 379)
ORDER BY a.created_at DESC LIMIT 0, 10
关于MySQL CASE 查询与 INNER JOIN,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/22907263/