MySQL, Query, Optimization, Web Performance, Database.
can only expand a simple query. If the subquery contains an aggregate function, GROUP BY, DISTINCT, it cannot be pulled up. Select * from t1 (select*from tab where id>10) as t2 where t1.age>10 and t2.age<25; Select*from t1,tab as t2 where t1.age>10 and t2.age<25 and t2.id>10; Specific steps: 1,