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Job Interviews: What is Normalization?


Job Interviews: What is Normalization?

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Steve Jones
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Comments posted to this topic are about the item Job Interviews: What is Normalization?

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andrew gothard
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The problem with anything but a fairly superficial description is, that in my experience, it's highly unlikely that the interviewer actually knows anything about normalization.

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xsevensinzx
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I normally take the same approach you mentioned Steve. I also add in the definition of denormalization to show I know the difference between the two.

Small typo in the article, "Do you there are various forms of normalization?" Think there should be a "know" between "you" and "there".
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I would give the very basic answer that it's how much data duplication exists(noun) or the practice of managing data elements to balance performance/data duplication/ease of use(verb). I couldn't give you any academic definition of any of the normal forms, I learned those just long enough to regurgitate them in college and promptly never had to care about the exact meaning of them again.
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Normalization, and data modeling in general, are good questions for intermediate level and higher database developers, because it's hard for a candidate to talk about without having actually having hands on experience. Again, open ended "explain to me" type of questions are better than questions that require a dictionary one sentence answer for which the candidate could have read up on the night before. Instead of asking "What is normalization?", instead say "Explain why normalization important?". Instead of asking "What is a clustered index?", instead say: "Tell me the advantages a clustered index has over a heap, or a non-clustered table?". I've found that the smartest folks, those who have been around the block a few times, actually enjoy the opportunity to explain things from the perspective of their past experience. Not only that, but those of us in high level IT positions need to explain concepts on a daily basis, it's just part of the job. When asked to explain something, frustration and blank stares on the part of the candidate suggests to me gaps in knowledge or at least a problematic personality.


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Steve Jones
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xsevensinzx - Thursday, January 11, 2018 6:14 AM
I normally take the same approach you mentioned Steve. I also add in the definition of denormalization to show I know the difference between the two.

Small typo in the article, "Do you there are various forms of normalization?" Think there should be a "know" between "you" and "there".


Thanks, fixed

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Jeff Mlakar
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I always like when interviewers ask this kind of question. It's a bit open ended so you have room to explain things and go in depth. Some basic white-boarding designing a basic schema is a useful exercise to gauge whether someone knows how to design tables or not.
Lynn Pettis
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I like the open-ended questions as well. My last interview for my current employer was interesting. He asked me 3 questions but I answered 10 questions. He asked number 1, my answer and explanation answered 1,2,3,4. He asked number 5, my answer and explanation covered 5,6,7. He asked number 8, and yes my answer covered 8,9,10. He was done in less than 15 minutes. And the rest is history as I am still work here.

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I've worked with a lot of very good database people that were pre courses (started our careers in the early 80's) so all self taught. They would definitely have some troubles explaining normalization in academic terms and would only use experiences. One of them had worked with Oracle from v4.0 to v8.0 and could not tell you what third normal form was yet always designed and built systems that worked and met normalization rules. He failed an interview because he could not name and academically explain 1st through 5th normal form. Yet he was the go to person for any of our DB designs as his systems always worked, worked fast and had no, I repeat no, data issues.
So I got him to read https://www.amazon.com/Manga-Guide-Databases-Mana-Takahashi/dp/1593271905 and with the information in the book he can now academically explain them and is now a senior database architect with a large Australian bank. Still has no formal IT education not certificates.

Frustrating that some recruiters believe that formal education and the ability to regurgitate learning is more important than experience and proof of value.



Dalkeith
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dogramone - Thursday, January 11, 2018 7:27 PM
Frustrating that some recruiters believe that formal education and the ability to regurgitate learning is more important than experience and proof of value.

Recruiters are recruiters - if I was trying to hire for a position in a discipline I knew nothing about I would probably default to qualifications as well.

Get someone with deep skills and has been round the block a few times into the interview who has both formal and good experience (if possible) and really have a general conversation on databases for an hour or two. Go light go heavy encourage discussion bring the conversation on and off topic see how the applicant responds see their flexibility see if they can react to what you are saying see if you can react to what they are saying.! I can see why you have these set questions as a starting point.

Its a relevant topic so a reasonable starting point and way better than "give an example of conflict in the workplace and how you dealt with it"

PS you are talking to someone who is after the fact trying to get some formal qualifications - I am enjoying the study and it is definitely more enjoyable to study something you have good experience in I am certain it is significantly improving my skill levels. If someone can learn everything without this great but for me I feel it is vastly increasing the speed of my learning in fact I don't think I would have ever learnt some of this stuff without formal study.

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