A Query Language for Statistical Databases
A Query Language for Statistical Databases
复制标题
统计数据库的查询语言
DOI：
--
复制
发表时间：
1985
期刊：
影响因子：
--
通讯作者：
G. Ozsoyoglu
中科院分区：
文献类型：
--
作者：
Z. Ozsoyoglu;G. Ozsoyoglu
在这一章中，我们描述了一个高层次的，面向屏幕的数据库查询语言，汇总表的例子（STBE）在统计数据库中的汇总数据进行操作。STBE使用集合函数、具有集值属性的关系和汇总表来提取汇总数据并将其格式化为表格形式。STBE类似于Query-by- Example，是另一种语言Aggregates-by-Example（ABE）的超集。汇总表显示的信息相当于一组关系。这种等价性允许STBE将查询中引用的汇总表转换为一组关系，并以统一的方式评估查询。STBE的表达能力至少是允许集值属性和聚合函数的关系演算的表达能力。将STBE与ABE、SQL进行了比较。简要讨论了STBE中的接入路径选择问题。
In this chapter we describe a high level, screen-oriented database query language, Summary-Table-by-Example (STBE) for manipulating summary data in statistical databases. STBE uses aggregate functions, relations with set-valued attributes and surrmary tables to extract and format summary data in tabular form. STBE is similar to Query-by- Example, and is a superset of another language, Aggregates-by-Example (ABE). Summary tables are shown to be information equivalent to a set of relations. This equivalency allows STBE to convert a summary table referenced in a query into a set of relations and to evaluate the query in a uniform manner. The expressive power of STBE is at least that of the relational calculus that allows set-valued attributes and aggregate functions. STBE is compared with ABE and SQL. Access path selection in STBE is discussed briefly.