数据库的模式结构对最终用户和程序员是透明的，他们见到的仅是数据库的外模式和应用程序。从最终用户角度看，数据库系统分为单用户结构、主从式结构、分布式结构和客户/服务器结构。-Database structure of the model is transparent to end users and programmers, they see only the external model and database applications. From the end-user perspective, the database system is divided into single-user structure, master-slave structure, distributed architecture and client/server architecture.