The lookup is an example of the Rails 3 relational algebra.
查询是Rails3关系代数的一个示例。
In relational databases, an operation in relational algebra.
在关系数据库中，关系代数中一种操作。
Rails 3 incorporates relational algebra, a DSL designed to express queries.
Rails3合并了 relational algebra，这是专门设计用于表示查询的 DSL。
The derived relational algebra operators are widely used in the relational database query languages.
关系代数的派生算子在关系数据库查询语言中得到了广泛应用。
Similarly, based on the medium set theory MS, the medium relational algebra can extend the capability of relational algebra.
同样地，中介关系代数以中介集合论MS为基础，扩充了关系代数的功能。
Is also a great introduction to this topic and shows the motivation and theory behind the "relational algebra" in ActiveRecord 3.
也是一个关于此话题的很好的介绍，解释了ActiveRecord 3中的“关系代数”背后的的动机和理论。
Its fuzzy knowledge representation, fuzzy relational algebra and the inaccurate reasoning implementation policies are described in detail.
详细介绍了其模糊知识表示、模糊关系代数及不精确推理的实现策略。
Aiming at how the DBMS query optimizer to generate the smallest cost query plan, optimization rules of the relational algebra expression are given.
针对DBMS查询优化器如何生成成本最小的查询计划问题，给出关系代数表达式的优化规则。
For example, Clojure has a delightful implementation of sets and operations on sets, as well as some quasi-relational algebra thrown in for good measure.
例如，Clojure有一个友好的Set及Set操作实现，以及一些准关系代数实现。
Finally, bitemporal relation is defined as the set of the temporal mapping tuple, and the bitemporal relational algebra operations are described formally.
最后，用时态映射定义的元组对双时态关系进行定义，并由此给出双时态关系代数运算的形式化描述。
This theoretical model allows, for example, that relational algebra operations to be replaced by more efficient equivalent operations whereas not interfere with the result.
例如，这种理论模型允许用更有效的等价操作来代替关系代数操作同时不影响结果。
Based on this model, this paper constructs two different kinds of medium relational database query languages: medium relational calculus and medium relational algebra.
给出了中介关系数据模型，在此基础上构造了两类不同的中介关系数据库查询语言：中介关系演算和中介关系代数。
Another benefit of the move to DB2 9 is the hybrid storage engine and a query optimizer that "understands" XML (mapping to relational algebra for queries involving XML).
迁移到DB 29的另一个好处是，混合型存储引擎和查询优化器“理解”XML，可以把涉及XML的查询映射为关系语法。
The system always adopt three kinds of technology that base on relational algebra operation, request decomposit localization, access route optimization to make optimization.
通常系统采用基于关系代数操作，请求分解定位和存取路径的优化三种技术对请求进行优化。
When relational tuples are flowing from mass storage to host via this filter, the unary operations of relational algebra for them such as projection and selection are completed parallelly.
使关系元组在由外存至主机的流动过程中就并行完成筛选、投影关系代数的一元运算。
SQL, which is a structured query language, has been an international standard language of relational database. This paper shows the corresponding relations between algebra of relations and SQL.
SQL是一种结构化的查询语言，已成为关系数据库的国际标准语言。
SQL, which is a structured query language, has been an international standard language of relational database. This paper shows the corresponding relations between algebra of relations and SQL.
SQL是一种结构化的查询语言，已成为关系数据库的国际标准语言。
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