| 1. | Relational algebraic operator this node represents
此节点表示的关系代数运算符。 |
| 2. | In relational databases , an operator in relational algebra
在关系数据库中，关系代数用的一种运算符。 |
| 3. | It is implied by the associative and commutative transformations permitted in relational algebra
它由关系代数中允许的关联转换和交换转换表示。 |
| 4. | Leap is an rdbms ( relational database management system ) implementing the relational algebra - a core part of relational database theory
Leap是一个rdbms ，它实现了关系代数，关系数据库理论的一个核心部分。 |
| 5. | 13 yoshinaga t , xu j , inoue k . a note on closure property of sublogarithmic space - bounded 1 - inkdot alternating turing machines with only existential universal states
例如，关系在关系代数运算下的结果仍为关系，我们称关系集合在关系代数运算下封闭。 |
| 6. | A clause is formalized as a relational algebra expression and evaluated by employment of relational algebra operations . 3 . the proof theory based on xml is presented
提出了利用关系代数运算实现xml查询子句求值的方法，并证明了该方法的正确性。 |
| 7. | To obtain efficient query execution , optimization is the most important step . many researches have carried on research on this subject by going deep into the bottom of query engine
传统的数据库查询优化主要是从查询的底层执行流程和实现技术出发，通过关系代数的手段进行理论上的探讨，而且大量研究集中在查询执行的语法分析阶段。 |
| 8. | An approach to formalize and evaluate relational algebra operations by means of xdd is presented . a query is formalized as one or more xml clauses and evaluated by employment of equivalent transformation of xdd
提出了根据关系代数表达式构造查询子句的方法，关系代数表达式可以用若干个xml子句描述，并通过等价变换得到查询结果，证明了该方法的正确性。 |
| 9. | In addition , because there is internal relationship between the formalism of relational database , " relational algebra " , and the clausal logic used by ilp , ilp methods can directly deal with mining task involved in multiple tables of relational database
此外，由于关系数据库的形式描述? “关系代数”与ilp的子句逻辑有着内在的关联性， ilp技术可被直接用于涉及关系数据库中多个关系(表)的数据挖掘任务。 |
| 10. | Second , the dissertation addresses the global query rewriting issues of the service oriented spatial data integration . query rewriting and optimization methods are presented based on equivalent transformation of relational operators . we study the data replication issues of spatial data services and presents strategies to deal with data fragmentation and service selection
其次,论文研究了面向空间数据服务集成的全局查询重构问题,在关系代数等价变换基础上提出了空间数据服务全局查询重构和优化方法,并提出了面向分布式空间区域查询的副本处理方法和资源选择策略。 |
