The difference between role, user and schema in Oracle, MySQL and PostgreSQL

0. Conclusion first

1. Database logic can be subdivided into: 角色, 用户, 数据库,模式
2. PostgreSQL and MySQL merged 角色and 用户, MySQL also merged 数据库,模式
3. Oracle merged 用户, 数据库,模式

1. Figure

1.1. Architecture

1.2.Users and roles

1.2.1.PostgreSQL

1.2.2.MySQL

1.2.3.Oracle

Reference article

What is the database schema?