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
- discrete source
- discrete space
- discrete space-time
- discrete spectrum
- discrete state
- discrete stochastic process
- discrete straight line
- discrete structure
- discrete subcategory
- discrete subgroup
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- discrete sum
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- discrete surface
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- discrete system
- discrete time
- discrete-time channel
- discrete-time control system
- discrete time control systems
- discrete-time decision process
- discrete time dynamical system
- discrete-time dynamical system
- discrete-time game
- discrete time method