基于数据库模式导航的select多表查询教学法

Didactics of Multi-Tables Select Sentence in SQL Based on the Navigation of Database Scheme

查询语句select是SQL的教学重点。基于关系自然联接运算的工作原理,本文提出借助关系数据库模式图中表之间的关联,来"导航"编写select查询语句方法,借助导航提示功能,在待求问题和select语句间构成映射,通过已知条件沿数据表间的关联来求未知,最终得到正确的select语句代码。本教学法在实践中取得良好效果。

The didactics of select sentence in SQL is a keystone. A new didactics is proposed for the didactics based on the relationships, ＂navigation＂, among the tables of a database scheme according to the principle of natural joint in relationship algebra. The mapping between a problem and a select sentence can be constructed by means of the navigation between tables, where a solution can be solved from a given condition. The effect of the didactics is remarkable.