理学 数据库系统 释 relational calculus 关系演算 一种抽象的关系数据语言，它通过数理逻辑中的谓词演算表达查询的要求。
calculus of relations 关系演算
数据库 数据库理论 释文 relational calculus 关系演算
- frequency error
- frequency estimator
- frequency factor
- frequency-following response
- frequency four-vector
- frequency fraction
- frequency function
- frequency histogram
- frequency hopping
- frequency hopping technique
- frequency hypothesis
- frequency hysteresis
- frequency indicator
- frequency instability
- frequency interval
- frequency inversion
- frequency jitter
- frequency judge approach
- frequency jumping
- frequency locking
- frequency-locking
- frequency matching
- frequency measurement
- frequency measuring equipment
- frequency meter