Database Normalization 1NF 2NF 3NF 

LOL Thank you !!

Exactly, I ask myself WHY? If they can simplify. Why make it more complicated than really is!!

They're not qualified (stupid) ​@@crislell

Great, and good luck !!

BRO SAME

@@feimimi U got this bro

Same Here :DDD

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This kind of feedback makes my day 😁!!

Thank you. Good luck with your course!

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My please! Thank you!

I really appreciate your feedback 😁!!

@@JesperLowgren I really appreciate your explanation!

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Thank you Robert, glad you liked it :).

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My pleasure Tyler. Thank you!

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Great, happy to help Jente.

That's great, thank you!

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Hi, here is the link to the video that addresses the 4th and 5th Business Normal Form: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-49BsrjjlObY.html

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I love to hear that 😁!

Thank you! Will do one of 4NF and 5NF, been thinking about it for a while.

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Hi Eva, a great observation and the answer is.... you could! Many organisations use services like Experian to validate addresses, and you could store a primary key for a particular address instead of the whole address. The same goes for employee. The question I would ask, and where I would draw the line, is how the data is used. Are there any benefits in creating a specific address table with a primary key? If yes, then I would do it, if no, I wouldn't. In most cases there probably wouldn't be a benefit and it would be easier to store the full address in attributes against an employee (or customer for that matter). Unless you are in the business of managing address data, like Experian, then you most certainly would. Hope this helps 😀.

@@JesperLowgren thank you for the answer and, yes, it helps. It's just that I'm the sort of person who tends to believe you can't learn computer programming if you don't understand how the current flows inside the computer if you understand what I mean, and that is the reason I'm not really able to draw some lines :))

Interesting thread. If it’s up to one to decide, in which NF do the scenarios fall? Are both 3NF of varying degrees? I understand it depends, but I am a bit confused on how to identify NFs then

Thank you Luggnugg 😁!

Good question! Looking back, it is somewhat ambiguous. If job names are stored in its own entity, and job name is the primary key (as opposed to job id), then Job Name is a legitimate Foreign Key in the Employee entity. But.... a better way is to define Job Names using the primary key Job ID. In this case, storing job name in an employee entity is incorrect, as job name is not defined using employee id. Hope this makes sense 😄.

Skill ID and Skill Name are repeating, so he had to rename them into Skill ID 1 Skill Name 1 Skill ID 2 Skill Name 2 so there are no repeating columns

@@alekizzu4705 No, he just placed the same data in a separate table, nothing changed at all. This is certainly not the repeating group issue.

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Hi, yes it is allowed and necessary. For example, in a PERSON entity, you might have a Foreign Key to a PERSON-GENDER entity, and to a PERSON-PREFERENCE entity etc. Each Foreign Key brings more meaning to the entity.

@@JesperLowgren oke, so only a primary key you can have once, but multiple foreign key, and candidaat keys can also be more because they are optional primary keys? im learning this cause in 2 weeks i got exame but the book i have from school, its bad, it has so much text in it and so much tekst between () that when you reed it the obviouse answer is sinking away in all the unnessesary tekst. this vid about normalisation is exctually good to follow and good to understand, im gonna write this down in my writingbook to learn.

@@2684dennis yes there can be multiple unique keys, and each unique key is a candidate primary key. But there can only be one primary key.

Hi Yves, yes a great observation and the answer is yes, you could split them and create an address entity with an address id, and then add address id as a foreign key to name. Some organisations do this when address is particularly important, such as sending items to a postal address. For example, using an external address validation service like Experian, and using the Experian address ID as a foreign key against a customer entity.

Thank you, yes I am planning to make a video on BCNF, 4NF, and 5NF soon!

Did you find a good resource for understanding this? I'm in the same position as you when you made this comment.

No, because each new "skill" will be represented as a new row in the Skill table

Hi Ariel, a job name might be Forklift Operator. An employee id might be 37 (John Smith). You can relate id 37 to job name Forklift Operator. But the job name Forklift Operator does not rely on employee id 37 (or any other employee id). The job name Forklift Operator can exist even if it is not related to any employee id; hence employee id does not depend on job name. Hope this makes sense. 😀

@@JesperLowgren I think i do understand it a bit more. Thank you for the clarification.

Yes it can! For example, a Contact with PK contact_id can be an FK in both a Leads table and an Opportunity table.

@@JesperLowgren wow thanks a lot! I had such a hard time and conflicting information on that as a 2 week old initiate.

@@JesperLowgren Now i just need to know what those diagrams with the Diamonds and rectangles and bubbles and numbers is called so i can find out what they mean. Im just starting the textbook: Fundamentals of Database Systems Seventh Edition.

Thank you !!😁