Since XML data can be very different from relational data, we need a dedicated language to handle XML data efficiently.
由于XML数据可能与关系型数据有很大的差异，因此我们需要一种专门的语言来高效处理XML数据。
The relational data model and use of the SQL language allows for enterprise level performance and scalability.
关系数据库模型和SQL语言的使用必须考虑到企业级性能和可伸缩性。
In a relational language, such a query would require a join that might span several data tables and system catalog tables.
而在关系语言中，这种查询需要进行也许跨越了多个数据表和系统目录表的联接。
Just like SQL is a query language designed for the relational data model, XQuery is a language designed specifically to query XML data.
正如SQL是为关系型数据模型设计的查询语言一样，XQuery是专为查询XML数据设计的语言。
This flexibility is reflected in the language support, which allows you to access relational data, XML data, or both at the same time. You can query your XML in any of the following four ways.
这样的灵活性表现在语言支持中，使您可访问关系型数据、XML数据，或者同时访问这两种数据。
Structured Query language (SQL) : a standardized language used to define objects and manipulate data in a relational database.
结构化查询语言(Structured Query Language,SQL)：一种标准化语言，用于在关系数据库中定义对象及操纵数据。
Traditional relational database query language SQL is designed for relational tables, and not suitable for XML or GML semistructured data;
传统的关系数据库查询语言SQL是针对平面的二维关系数据而设计的，并不适合XML/GML半结构化数据的查询；
Traditional relational database query language SQL is designed for relational tables, and not suitable for XML or GML semistructured data;
传统的关系数据库查询语言SQL是针对平面的二维关系数据而设计的，并不适合XML/GML半结构化数据的查询；
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