摘要: explain中的每个列的信息: SET SESSION optimizer_switch='derived_merge=off'; #关闭mysql5.7新特性对衍生表的合并优化 EXPLAIN SELECT (SELECT 1 FROM actor WHERE id = 1) FROM (SEL 阅读全文
posted @ 2024-01-16 00:22 程序马2023 阅读(44) 评论(0) 推荐(0)