2
votes
2answers
46 views

Is there a good way to select a row where the key represents the lower bound of a range?

I am designing some tables and a number of the tables have as the key a lower and upper bound which never overlap. I want to query by a value that can fall withing any of those ranges. If I keep both ...
0
votes
1answer
774 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?
0
votes
1answer
37 views

Modify legacy table schemas that have no primary key

I've been tasked with updating our database (SQL Server 2008) so that every table in it has a proper primary key defined. Due to various reasons over the years we have somehow built up some legacy ...
3
votes
1answer
127 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 ...
4
votes
2answers
180 views

How many fields is too much for a primary key?

I am creating a table to store information about the placement of objects in a grid (game map). For example, I have a 10x10 grid and I want to store, in the database, that cell (5,5) has a blue box, ...
0
votes
1answer
327 views

How SQLite index ID (or line number)

SQLite is based on a flatfile, and store virtual tables in a flatfile (I think based on offset, correct me if I'm wrong). But how it index the Primary Key (ID), which I think is identical to line ...