如果列出“节点收藏”中对应的主题,如何书写最有效率的 SQL? - V2EX
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如果列出“节点收藏”中对应的主题,如何书写最有效率的 SQL?
daijia1123
2015-05-11 17:13:24 +08:00
3265 次点击
这是一个创建于 3836 天前的主题,其中的信息可能已经有所发展或是发生改变。
当前节点收藏中是列出收藏的节点,点击节点后才能查看相应主题。
如果想进入后,直接按时间顺序列出收藏节点的相应主题该如何做最有效率?SELECT * FROM Topics WHERE id IN (SELECT id FROM nodes WHERE userid=uid),这种方式感觉效率不会高。
数据库结构是否也有特别需要注意的地方(除了索引等)?
节点
列出
select
3 条回复
2015-05-11 17:31:16 +08:00
1
anoymoux
2015-05-11 17:30:20 +08:00
1
SELECT * FROM Topics t,nodes n WHERE
t.id
=
n.id
and n.userid=uid
2
anoymoux
2015-05-11 17:30:49 +08:00
1
SELECT t.* FROM Topics t,nodes n WHERE
t.id
=
n.id
and n.userid=uid
3
fangjinmin
2015-05-11 17:31:16 +08:00
1
设计上没有什么问题。问题是你用了子查询,一般来说不会快。这样会好一些,select * from topics join nodes on (
topics.id
=
nodes.id
) where nodes.userid=uid,然后nodes的userid和id都加上索引。
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