How to design a survey database schema that includes matrix questions??

I'm working on a complex survey form for a client and will be used only once, the survey is going to be anonymous so...

Analysis of SQL Schema: what is the purpose of loop in ProductCategory of AdventureWorks??

I want to understand the purpose of the loop in the ProductCategory table. AdventureWorks is a sample database here ...

Social web application database design: how can I improve this schema??

Background I am developing a social web app for poets and writers, allowing them to share their poetry, gather feed...

How to rollback a specific migration??

I have the following migration file db\migrate\20100905201547_create_blocks.rb How can I specifically rollback that...

Storing email messages in a database?

What sort of database schema would you use to store email messages, with as much header information as practical/pos...