Research into Declarative, Object-Oriented Languages for Programming Data and Knowledge

关系型查询语言，如SQL，是声明性编程的早期成功案例。然而，随着新的应用领域的发展，人们发现关系系统的不足。它们在结构和语言方面的局限性导致了数据库和演绎数据库的出现。当数据的结构是已知的，并且数据访问路径和检索方法可以在系统开发时确定时，面向对象数据库（简称O-O）是有效的。基于逻辑的演绎DBMS适用于定义不太明确的情况；事先不知道将被询问的所有问题的情况。灵活性对于现代DBMS来说是极其重要的，特别是当用户缺乏关于应用程序域结构的详细知识时。由于这个原因，每当需要对数据进行智能处理时，传统上就使用基于逻辑的语言。另一方面，这些语言中固有的扁平数据结构不适合许多科学应用，如CAD/CAM设计，建模敏捷制造处理等，其中数据具有复杂且已知的内部结构。

Relational query languages, such as SQL, were the early success stories of declarative programming. However, as new applications areas have developed, relational systems have been found wanting. Their limitations--both structural and language related--have led databases and deductive databases. Object-oriented databases (abbr., O-O) are effective when the structure of the data is well- known and the data access paths and retrieval methods can be determined at system development time. Deductive DBMS, based on logic, are appropriate in less well-defined situations; situations where one does not know before-hand all the queries that will be asked. Flexibility is extremely important for modern DBMS, especially when the user lacks detailed knowledge about the structure of the application domain. For this reason, logic-base languages have traditionally been used whenever intelligent processing of data was required. On the other hand, flat data structures inherent in such languages are ill-suited for many scientific applications, CAD/CAM design, modeling agile manufacturing processing, etc., where data has complex and known internal structure.