Question

The question is how database design should I apply for this situation:

main table:

ID | name | number_of_parameters | parameters

parameters table:

parameter | parameter | parameter

Number of elements in parameters table does not change. number_of_parameters cell defines how many parameters tables should be stored in next cell.

I have problems to move from object thinking to database design. So when we talk about object one row has as much parameters as number_of_parameters says.

I hope that description of requirements is clear. What is the correct way to design such database. If someone can provide some SQL statments to obtain it it would be nice. But the main goal of this question is to understand how to make such architecture.

I want to use SQLite to create this database.

Answer 1

The relational way is to have two tables. The main table has an ID, name and as many other universally-present parameters as possible. The parameters table contains a mapping from an ID in the main table to a parameter name and a parameter value; the main table ID should be a foreign key, and the combination of ID and name should be unique.

The number of parameters can be found by just counting the number of rows with a particular ID.