The industry-wide adoption of graph databases has been hindered due to the fragmentation in syntax and semantics of available graph query languages. As a result, several projects have been proposed by industry and academia to develop a standard query language by integrating features from existing practical graph query languages. A significant factor that can impact query language integration is the lack of common theoretical language formalisms. We propose common formalisms by extending conjunctive queries and union of conjunctive queries with Tarski’s relation algebra (CQT/UCQT). We use common graph query patterns to compare the expressive power of (CQT/UCQT) with two practical graph query languages - $Cypher$ and $PGQL$. The query languages are analysed on the core features of graph pattern matching and graph navigation, revealing the common and exclusive characteristics for these languages. Overall, our study serves as a formal basis for comparing existing graph query languages and assists the move towards query language integration and interoperability between available graph database technologies.

由于可用图查询语言的语法和语义碎片化，图数据库在行业范围内的采用受到了阻碍。因此，工业界和学术界提出了几个项目，通过集成现有实用图查询语言的特征来开发标准查询语言。影响查询语言集成的一个重要因素是缺乏通用的理论语言形式。我们通过使用 Tarski 的关系代数 ( CQT / UCQT )扩展联合查询和联合查询来提出通用形式。我们使用常见的图查询模式来比较（CQT / UCQT）与两种实用的图查询语言的表达能力-$C是磷H\mathrm{电子}r$ 和 $磷G问升$. 对查询语言进行了图模式匹配和图导航的核心特征分析，揭示了这些语言的共同特点和独有特点。总体而言，我们的研究是比较现有图形查询语言的正式基础，并有助于实现可用图形数据库技术之间的查询语言集成和互操作性。