数据库理论中数据库用户和数据库模式并没有必然的联系，详细的数据库模式解释可以在这里找到：
http://stackoverflow.com/questions/2674222/what-is-purpose-of-database-schema
A database schema is a way to logically group objects such as tables, views, stored procedures etc. Think of a schema as a container of objects.You can assign a user login permissions to a single schema so that the user can only access the objects they are authorized to access.
Schemas can be created and altered in a database, and users can be granted access to a schema. A schema can be owned by any user, and schema ownership istransferable.
也就是说数据库模式可以创建修改，并且可以给不同的用户访问也可以赋予不同的用户。
而Oracle文档《Concepts》中的解释是这样的：
A schemais a collection of logical structures of data, or schema objects. A schema is
owned
by a database user and has the same name as that user. Each user owns a single
schema.
虽然Oracle中模式也是数据对象的集合，但是在这里一个用户对应了一个模式，一个模式只能被一个数据库用户所拥有。
原文：http://blog.csdn.net/lubinsu/article/details/46992353