理学 数据库系统 释 relational algebra 关系代数 一种抽象的关系数据语言，它通过对关系的运算来表达查询。
relational algebra 关系代数
数据库 数据库理论 释文 relational algebra 关系代数
- tropical zone
- tropical zone in China
- tropic movement
- Tropic of Cancer
- Tropic of Capricorn
- tropics
- tropinone
- tropism
- tropistic movement
- tropocollagen
- tropoelastin
- tropolone
- tropomyosin
- tropone
- troponin
- tropopause
- tropopause fold
- tropopause inversion layer
- troposcatter
- troposphere
- troposphere chemistry
- troposphere delay correction
- tropospheric
- tropospheric attenuation
- tropospheric biennial oscillation