对于MySQL而言，“database 数据库” 和 “schema 模式” 是同一件事。具体区分如下表：
In MySQL:
- server instance == not identified with catalog, just a set of databases
- database == schema == catalog == a namespace within the server.
- user == named account, who can connect to server and use (but can not own - no concept of ownership) objects in one or more databases
- to identify any object you need (database name + object name)
In Oracle:
- server instance == database == catalog == all data managed by same execution engine
- schema == namespace within database, identical to user account
- user == schema owner == named account, identical to schema, who can connect to database, who owns the schema and use objects possibly in other schemas
- to identify any object you need (schema name + object name)
详细阅读：
1.What's the difference between a catalog and a schema in a relational database?
2.Relationship between catalog, schema, user, and database instance
