It is far better to have an excellent Database Design and a crappy Application Layer, than an excellent Application Layer with a crappy Database design.

Why is that?  Simply put, you can always skim your Application code off the top and write a new one.   But you can not simply swap out the Data Layer without completely undermining the Application.

The closer we can model our business logic in the database itself – the better it is for the business.  When new unforseen questions arise about the business, we can always run adhoc queries from a well designed database schema to get the answers.

For example:

• Who are our top customers?
• What is revenue month over month?  Year over year?
• What is the distribution of sales by product types across all income channels?
• What percentage of our customers pay late over 30 days?
• What time of day do we have the most volume?
• What is the percentage of repeat customers vs first time buyers?
• Has revenue gone up since the last website revamp?

All of these questions are very easily answered with a little SQL magic, when the database is well designed.  And all of these questions can be horrendously hard to answer when it is not.

For all important systems, the Data Layer must be King.