论文标题
关系图：非杰出关系查询的图案图形图表
Relational Diagrams: a pattern-preserving diagrammatic representation of non-disjunctive Relational Queries
论文作者
论文摘要
通过逻辑表达分析关系语言，可以很好地理解。关系模式的模糊概念不太理解甚至是正式的。什么是查询模式？我们如何推论各种关系语言的查询模式，无论其语法及其程序性或声明性质如何？在本文中，我们用查询模式的概念形式化了查询模式的变体之间的映射。这种形式主义使我们能够分析关系查询语言的相对模式表达性，并创建具有逻辑表达相同的语言层次结构，但表达方式不同。在此分析中，关系计算比关系代数的基本运算符表达更多的模式。我们还为安全的关系演算做出了直观，完整和声音的图表表示，不仅在关系上完成，而且还可以表达所有逻辑模式，用于非分散性关系计算的大而有用的片段。在我们所知道的所有关系查询的所有图表表示中，这是唯一在关系上完成的唯一一种，并且可以代表非分散片段中的所有逻辑模式。
Analyzing relational languages by their logical expressiveness is well understood. Something not well understood or even formalized is the vague concept of relational query patterns. What are query patterns? And how can we reason about query patterns across different relational languages, irrespective of their syntax and their procedural or declarative nature? In this paper, we formalize the concept of query patterns with a variant of pattern-preserving mappings between the relational atoms of queries. This formalism allows us to analyze the relative pattern expressiveness of relational query languages and to create a hierarchy of languages with equal logical expressiveness yet different pattern expressiveness. In this analysis, relational calculus can expressive more patterns than the basic operators of relational algebra. We additionally contribute an intuitive, complete, and sound diagrammatic representation of safe relational calculus that is not only relationally complete, but can also express all logical patterns for the large and useful fragment of non-disjunctive relational calculus. Among all diagrammatic representations for relational queries that we are aware of, this is the only one that is relationally complete and that can represent all logical patterns in the non-disjunctive fragment.
