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.

• 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。