摘自：https://www.quora.com/What-is-a-schema-in-a-MySQL-database
What is schema?
In MySQL, physically, a schema is synonymous with a database. You can substitute the keyword schema instead of database in MySQL SQL syntax, for example using create schema instead of create database.
Some other database products draw a distinction. For example, in the Oracle Database product, a schema represents only a part of a database: the tables and other objects owned by a single user.
What is a Data Model?
A data model is an abstract model, that documents and organizes the enterprise data for communication between developers. Most of the times a data model is reprensented in a diagram. A data model is used as a plan for developing software, specifically how data is stored and accessed. A data model of your database can support the analysis, design, documentation and migration of underlying database structures.
How to design database/schema?
In software engineering, data modeling is the process of creating a data model for an information system. This is done by applying formal data modeling techniques.
There are many tools which can help you with modeling such as SQLDBM.
SqlDBM initially started out with inbuilt support for Microsoft’s SQL Server only.
But of course, due to large number of requests for MySQL support from our users, we have been working hard to expand our product.
And now, we are very proud to announce that SqlDBM offers support for MySQL – one of the most popular open-source databases in the world.
You can now model and design your MySQL database/s directly on SqlDBM . And of course, you can take advantage of and adapt SqlDBM features into your MySQL database such as Subject Areas, Relationships, Diagrams, View Modes, etc.
SQLDBM offers you an easy, convenient way to design your database absolutely anywhere on any browser, working away without need for any extra database engine or database modelling tools or apps. Use SQLDBM to design and manage both large and small databases and data models on the fly. All while incorporating any needed database rules and objects such as database keys, schemas, indexes, column constraints and relationships.