Then i gave out the ten steps when a data base marketing system is being built in sedan market . in chapter four , i talked about how do we collect and collate the data used in sedan marketing system , studied the discrimination and the excerption of primary data and secondary data problem 然后论述了在轿车行业开发数据库营销系统的十个步骤；在第四章，主要是研究在轿车营销数据库系统中，所需数据的分类以及收集、整理等方面的内容，研究了初级数据、次级数据的甄别选录等问题。
