It goes further by mentioning that it could be any type of database: relational (object-relational) or non-relational.

并且还进一步提到可以是任何类型的数据库：关系(对象-关系)或非关系的。

youdao

Support for a variety of data sources, including relational database management systems (DBMSs), non-relational DBMSs, files, XML documents, and others.

支持各种数据源，其中包括关系数据库管理系统(DBMS)、非关系DBMS、文件、XML文档和其他数据源。

youdao

Because we are using Hibernate as our provider, we cannot choose a non-relational database like Google App Engine.

因为我们使用Hibernate作为我们的提供者，我们不能选择非关系型数据库，比如Google App Engine。

youdao

For example, customer data could go into a relational database, linked to a non-relational database for unstructured data such as product reviews and recommendations.

FORBES: What You Need to Know About NoSQL Databases