[英]MySQL sub-query optimization
I've got a query that is running awfully slow: 我有一个运行非常慢的查询:
SELECT *
FROM games
WHERE games.platform =13
AND games.id NOT
IN (SELECT game_id
FROM collections
WHERE collections.user_id =1)
I attempted to rewrite it as a left join but it's returned 0 results: 我试图将其重写为左连接,但返回0个结果:
SELECT *
FROM games
LEFT JOIN collections ON collections.game_id = games.id
WHERE collections.game_id IS NULL AND collections.user_id = 1 AND games.platform = 13
ORDER BY games.name ASC
Could someone point out my error here? 有人可以在这里指出我的错误吗?
SELECT games.*
FROM games
LEFT JOIN collections
ON collections.user_id = 1
AND collections.game_id = games.id
WHERE games.platform = 13
AND collections.game_id IS NULL
ORDER BY games.name ASC
you need indexes on 你需要索引
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