数据库查询优化包括两方面，基于代价的查询优化和基于响应时光的查询优化，可以有效地提高庞杂查询的效力。

There are two methods of database query optimization: cost-based and response time-based query optimization, all of which can improve the efficiency of complex query.

youdao

数据库查询优化包括两方面，基于代价的查询优化和基于响应时光的查询优化，可以有效地提高庞杂查询的效力。

There are two methods of database query optimization: cost-based and response time-based query optimization, all of which can improve the efficiency of complex query.

youdao