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#1 summer_breeze   User is offline

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Attention: Systems and Database Designers

Posted 01 July 2013 - 12:33 AM

Good day! I just wanted to ask a few questions to some professional systems and database designers out there.
Based on your work experience:

1. Describe the process you use for logical design.
2. How do you transform your conceptual data models to relational schema?
3. What is the role of CASE tools in this process?
4. To what level do you use normalization?

Thanks for alloting your time in answering.
You don't need to elaborate your answers, but if you do, I highly appreciate it. :)

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Replies To: Attention: Systems and Database Designers

#2 baavgai   User is offline

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Re: Attention: Systems and Database Designers

Posted 01 July 2013 - 05:31 AM

1. Collect the data. Find out every single piece of information that you'll need to store. Users don't know or understand databases, but they know what they want to see. They often have reports they want at the end of the process. Users also don't see the big picture and make lots of assumptions; your job is to pin them down. e.g. You: Wait, the customer can have multiple addresses in the system? User: Of course. You: Yeah, thanks for mentioning that...

2. Once you have all the data, you figure out what needs to be stored, what can be shared, and what can be inferred. The data will offer the patterns that dictate structure.

3. Suits like pictures. Diagrams are for meetings. I'll usually work things out with a text editor and a test database. I might make a picture later in process to play show and tell and, based on that, make changes. Tools can sometimes lock you into design choices you don't really want. This never happens if you can do it yourself. You have to asses how much work a tool will save versus how much fiddling you'll ultimately end up doing because of it.

4. Hopefully, a sane level. You can go nuts with normalization. Look at how much data is repeated in a address: city, state, zip. Let's make a city_state_zip table and use city_state_zip_id... The point of normalization is to prevent inconsistencies due to data duplication. If you achieve this goal, you're probably doing fine.
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#3 DarenR   User is offline

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Re: Attention: Systems and Database Designers

Posted 01 July 2013 - 06:27 AM

1. collect data and arrange it in a logical order

2. decide what is required data and what is junk. decide how you want the data to connect to each other.

3. we dont use CASE. We are a small firm (300+ people) so we just implement our designs

4. we use normalization all the time so we dont have to guess what the databases are supposed to look like or work like when multiple people are creating the databases. we make them all the same so we eliminate guess work
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