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
- Daoqing chanting
- Daoqing opera
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- Daoqing operetta of northern Shaanxi
- Dao Ru'an
- Daoshan Clear Talk
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- daotan decoction
- Daotang He
- Daouda Sow
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- Daoxian human remains
- Daoxin
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- Dapan Mountain Scenic and Historic Area
- Dapanshan Dao