1
vote
1answer
45 views

one to one relationship

This is my database structure: Users {user_id, username} Profiles {profile_id, user_id, user_views} My question is: If I do it the way mentioned above, should I to set user_id as primary key or ...
2
votes
1answer
28 views

NEWB Getting to KNow New Database and Understand Where Relationships Are

I'm teaching myself SQL using MYSQL and a textbook. While working through the textbook I'm using a database I'm kinda familiar with - an exported copy of my CMS driven websites database. My website ...
0
votes
1answer
555 views

Candidate key = Key = Minimal Superkey?

I got a little confused by all these keys. As I understand A key of a relational schema = The minimal subset of a superkey that is still a key = A candidate key Is this correct or not?
2
votes
2answers
214 views

MySQL - Normalization over meaningless data - Compound Primay Keys or Surrogate ID field

Please forgive my title; if you have a suggestion for it, feel free to comment. I have a database: DROP TABLE IF EXISTS `books`; CREATE TABLE `books` ( `isbn` VARCHAR(255) NOT NULL, `title` ...
3
votes
1answer
112 views

Optimised Schema for City-to-City Distance Table

This is my first question, forgive me if this question is simple. I'm stuck here, trying to implement the relations for the data represented below. I want to scale it vertically (new rows), instead of ...
1
vote
1answer
97 views

Can I place the attribute in the Entity, when the foreign key is also already present?

I am using DBdesigner Fork for generating ER diagram. I have the 'Company' as an entity for which can I place the attribute of 'idShares', despite of having the foreign key of Shares Entity in the ...