In my software team as part of the interview we test for Databases understanding.
We present - a very poor design (think CRM type application) and ask them to improve the design, after around 30 mins of thinking time.
We then ask them more questions based on what they talk about.
We are probing for understanding of
- Performance V Normalistion
- Key Design and Referenital Integrity
- Places for improvment -ie Alternative DB Structure - Triggers, View, Procuedures
- Areas that are weak in the design - how to overcome many to many relationships
- How this affects the server - maintaince
- Data Security Issues
- Application Security Issues
We as a team have then thought about what we would consider to be Junior/Senior/Architect type answers to these types of questions.
- Performance v Normisalation -
would see the issue in the first place and be able to discuss why (Junior)
would recommend 4/5 NF but understand the issue with performance would they denormalise and understand how to articulate the issue(Senior)
would they recommend a different type of design eg Star Schema and discuss the implications on many levels(Architect)
- Key Design and Referential Integrity
Would see the ref integrity is needed to enforce data relationships and be able to discuss this but would not see the issue with Key Choice and Design (Junior)
Would discuss issues to do with data volumes and data types v looking for natural keys in the data and would be able to discuss why they are looking at these - and the issues that follow with referential integrity (Senior)
Could argue various viewpoints to do with Keys and Integrity and be able to come up with various actual models for fast design (Architect)
You get the picture.
If you want me to add more then post comment and will detail what we think about the rest but just included the first two to give you the idea on what we thought.
The point is to think about the 1. the questions 2. We as a team have then thought about what we would consider to be Junior/Senior/Architect type answers to these types of questions.
I emphasis the team as the candidate and the team have to be confident in the skills of the person coming in, and if they have come up with what they see as answers to different levels the person coming in will hopefully fit with team better. It also gives the team the ability to influence the candidate choice. They also nominate a person to be on the question panel. Helps a lot with team buy-in.