查询优化是数据库管理体系设计和实现所采取的一项主要技术，也是影响数据库体系机能的一个主要因素。

Query optimization is not only an important technology used in the design and realization of database management system, but also an important factor that affects the performance of database system.

youdao

查询优化是数据库管理体系设计和实现所采取的一项主要技术，也是影响数据库体系机能的一个主要因素。

Query optimization is not only an important technology used in the design and realization of database management system, but also an important factor that affects the performance of database system.

youdao