理学 数据库系统 释 query optimization 查询优化 查询优化旨在通过选择有效策略，对给定的关系表达式求值，使得查询代价最小。
数据库 数据库管理系统及其实现技术 释文 query optimization 查询优化
- head loss
- head, magnetic head
- Headman
- head mask of opera
- headmaster
- headmaster-in-charge system
- head mounted display
- head mounted display, HMD
- head normal form
- Head of Alexander
- head of an arrow
- head of comet
- head office
- Head Office of Xinhua Bookstore
- head of hydraulic turbine
- head of hydroelectric power station
- head of painted pottery goddess
- head of pump
- head of the Directorate of Education (official name)
- head of the line processor sharing
- head-of-the-line processor sharing
- Head-on
- head-on collision
- head-on cross-section
- head-on encounter