MySQL性能优化之道

* from test1 where EXISTS (select * from test2 where id2 = id1 ) select * FROM test1 where NOT EXISTS (select * from test2 where id2 = id1 )

用join代替

 select id1 from test1 INNER JOIN test2 ON id2 = id1 
 select id1 from test1 LEFT JOIN test2 ON id2 = id1  where id2 IS NULL

 

MySQL性能优化之道

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