mysql

#分页查询:

1,根据自增且连续主键排序的分页查询

一般: select * from t1 limit 99000,2;
优化: select * from t1 where id >99000 limit 2;

2,查询根据非主键字段排序的分页查询

一般: select * from t1 order by a limit 99000,2;
优化: select * from t1 as a join( select id from t1 limit 99000,2) as b on a.id=b.id