Web数据库多表查询的关键技术与优化

The key technology and optimization of query in Multi table Web Database

为了满足面向专业的Web数据库通用信息查询服务需要 ,弥补目前这一方面存在的一些不足 ,作者研究了Web数据库多表查询中的关键技术与优化方法 .即通过查询界面的设计原则、实现方法 ,引导查询人进行正确的操作 ,以获得与期望相符的查询结果 ,同时还对界面进行了优化 ,压缩了界面HTML文件的大小 ,降低了网络传输所带来的延时 .此外 ,还讨论了SQL语句的形成 ,以子查询方式优化SQL语句 ,提高了查询的效率 ,改善了Web数据库服务器的性能 .特别是当数据库中的记录越多时 ,Web数据库服务器性能的改善越明显 .在查询结果界面中 ,通过引入拖拽机制与隐藏 /显示机制来提高查询结果界面的交互性 。

To meet the demand of general information query service in the specialized Web database and supply some gaps in this service, the key technology and optimization method of multi table query in Web database are discussed in this paper. The design guideline of query interface is brought forward. The implementation of interface is described. It leads user to make correct operation so that the result can correspond with the user′s expectation. The optimization of interface is realized so as to decrease the delay of Internet transmission by compressing the size of interface HTML file. The formation of SQL statements is discussed. For enhancing the efficiency of information query and improving the performance of Web database server, the SQL statements are optimized by means of sub -query. Specially, the more records the database contains, the more obviously the performance of server will be improved. The interaction, such as drop and drag, visible/hidden etc, is introduced in the result interface so that users can query more effectively.