摘要
给出了把含有混合量词的元组演算式及含有聚集运算的关系代数式转换为常规的关系代数式的方法;从而,为用通常的关系数据库查询语言(如dBASEⅢ)实现非简单查询提供了一个有效的途径。
This paper gives a general method representing relation data base query as a conventional relation algebra expression. Mainly, the paper has given the method that converts tuple calculus expression con taining multi-guantifiers or relation algebra expression containing group-by operation to conventional relation algebra expression; therefore it has offering a efficient way that realizes non-simple queries with usual relation data base query languages (e · g · dBASE Ⅲ ).
出处
《沈阳工业大学学报》
EI
CAS
1992年第1期47-56,共10页
Journal of Shenyang University of Technology
关键词
数据库
关系代数
转转
查询语言
data libraries
relational algebra
conversion
