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
- underwater photogrammetry
- underwater photographic camera
- underwater photography
- underwater piezoelectric sensing technology
- underwater pipeline
- underwater positioning
- underwater pressurization system
- underwater processing system
- underwater propulsion
- underwater raman spectroscopy
- underwater reef blasting
- underwater robot
- underwater rockplug blasting
- underwater sampling
- underwater sensing technology
- underwater sensor network
- underwater signaling apparatus
- Underwater Site of Dongjiao Village in Xiaolian Island of Pingtan
- Underwater Site of Haitan Strait at Pingtan
- underwater sound countermeasure
- underwater sound projector
- underwater sound propagation
- underwater sound recorder
- underwater sound transducer
- underwater span-connecting tube