For SaaS solution, we need to cater many customers database with a single code base application

There are several type of multi-tenant architecture for database.

1. different database
2. shared database server but different schemas (or “database”)
3. shared database and shared schemas

Some further readings

1. https://web.archive.org/web/20110311185417/http://msdn.microsoft.com/en-us/library/aa479086.aspx
2. https://www.mysql.com/products/cluster/ -partition/shards