查询是Rails3关系代数的一个示例。
在关系数据库中，关系代数中一种操作。
In relational databases, an operation in relational algebra.
目的提出基于关系代数理论的关联规则挖掘算法。
Aim To put forward association rule mining algorithm based on relation algebra theory.
本文重点介绍了适合于时态数据库的时态关系代数。
It discuss the temporal relation algebra operations fit to temporal database.
结果证明时态关系代数运算与传统关系代数运算是相容的。
The conclusion is that the algebra operations of temporal relation and traditional relation are similituded.
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。
The derived relational algebra operators are widely used in the relational database query languages.
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。
Its fuzzy knowledge representation, fuzzy relational algebra and the inaccurate reasoning implementation policies are described in detail.
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。
This theoretical model allows, for example, that relational algebra operations to be replaced by more efficient equivalent operations whereas not interfere with the result.
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。
Similarly, based on the medium set theory MS, the medium relational algebra can extend the capability of relational algebra.
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。
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.
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。
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.
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。
The system always adopt three kinds of technology that base on relational algebra operation, request decomposit localization, access route optimization to make optimization.
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。
Aiming at how the DBMS query optimizer to generate the smallest cost query plan, optimization rules of the relational algebra expression are given.
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。
Finally, bitemporal relation is defined as the set of the temporal mapping tuple, and the bitemporal relational algebra operations are described formally.
以综合地理学、地图制图学、关系代数为理论基础，可以用分析组合法、综合法进行基本信息元制图。
Research region can be mapped into series BP under the principle of synthetic geography and cartography.
也是一个关于此话题的很好的介绍，解释了ActiveRecord3中的“关系代数”背后的的动机和理论。
Is also a great introduction to this topic and shows the motivation and theory behind the "relational algebra" in ActiveRecord 3.
根据这些算法和关系代数等价定理，给出了对关系代数查询树进行逻辑优化的规则，并证明了逻辑优化的正确性。
With these algorithms and the equivalence theory, the several rules to logically optimize the accessing trees were presented and the correctness for the logical optimization was proved.
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。
Based on this model, this paper constructs two different kinds of medium relational database query languages: medium relational calculus and medium relational algebra.
答案要看 simplex算法背后采用的代数关系，但是有关它是如何工作的解释已经超出了本文的范围。
The answer is in the algebra behind the simplex algorithm, but explaining how it works is beyond the scope of this article.
本文主要研究了等价关系的交并运算，建立了等价关系对于交并运算的代数结构。
This Paper study the intersection and union operations, with it establishes the algebraic structure of equivalence relations.
本文用生成元和定义关系的方法，对每个可解可补李代数给出一个定义矩阵。
A defining matrix is given for the solvable and complemental Lie algebras with a generator relation method.
代数群的连通正规闭子群与李代数的理想之间有很特殊的关系。
There are particular relations between the closed connected normal subgroups of algebraic groups and the ideals of Lie Algebras.
讨论了线性代数中矩阵的秩、向量组的秩与线性方程组的秩之间的关系。
This paper describes the relationship between the rank of matrix, the rank of vector group and liner equation group in the linear algebra.
粗糙集代数关系的图结构分析是粗糙集理论中又一研究方向。
The graphic structure analysis for algebraic relationship of rough sets is a new research direction of the rough set theory.
在本章最后一节，讨论了以上各类代数相互之间的关系。
In the last section of this chapter, the mutual relations of the above various algebras are discussed.
在有单位元的交换环上，可应用生成元和定义关系的方法给出仿型李代数的定义。
On commutative ring with the identity, the definition of affine Lie algebras was given by applying the means of generator and defining relation.
为了解决正交拉丁方完备组问题，利用代数方法讨论了拉丁方与正则群的关系。
In order to solve the problem of complete system of orthogonal Latin squares, relation between Latin square and permutation groups is discussed by using method of algebra.
半群的研究在代数学的理论研究中占有很重要的地位。 其中格林关系在半群理论的研究中有着重要的意义。
The research of semigroup plays an important role in the research of the theory of algebra, and the Green's equivalences are especially significant in the study of semigroups.
最后讨论两种代数之间的关系，并求出函数展开式系数之间的转换矩阵。
By using discussing the relationship of two-kinds of algebra, the conversion matrix of expansion coefficients are derived.
最后讨论两种代数之间的关系，并求出函数展开式系数之间的转换矩阵。
By using discussing the relationship of two-kinds of algebra, the conversion matrix of expansion coefficients are derived.
应用推荐