摘要： 已经存在的SQL 聚集函数在计算百分比方面有明显的限制，提出2种水平与垂直百分比聚集函数用于计算百分比。新的聚集函数容易使用，有广泛的用途，可以被用于作为一种框架去研究百分比查询，能有效地生成SQL 代码。实验研究给出百分比聚集方法与SQL/OLAP聚集方法的执行性能，结果显示这2种方法在性能上比SQL/OLAP聚集方法有一定的改善。
关键词:
关系数据库,
结构化查询语言,
查询处理,
聚集函数,
百分比聚集
Abstract: Current SQL aggregate functions have evident limitations for computing percentages. This paper proposes two SQL aggregation functions for computing percentages. The two novel aggregation functions are easy to use, have wide applicability and can be efficiently evaluated. They may be used as a framework to study percentage queries and to generate efficient SQL code. Experiments compare the proposed percentage aggregations against queries using SQL/OLAP aggregations. Experimental results show that both proposed aggregations are significantly faster than existing SQL/OLAP aggregation functions.
Key words:
relation database,
SQL,
query processing,
aggregation functions,
percentage aggregation
中图分类号:
肖 杰;谢 东;曾玢石. SQL聚集函数扩展[J]. 计算机工程, 2009, 35(16): 73-75.
XIAO Jie; XIE Dong; ZENG Fen-shi. Extension of SQL Aggregation Functions[J]. Computer Engineering, 2009, 35(16): 73-75.