Stuck in database structure with many kind of tables [duplicate]

Question

I'm creating a structure of DB by E/R Diagram, but I'm stuck since some days on this problem. Probably I'm wrong in the way I'm doing it, so if you think I can do it in a better way, would be lovely :)

The scenario is: I have N users who owns N sensors, not all the sensors (in the future could increase to 300 kinds of sensors) have the same features(columns), so I suppose I need a table for each sensor and then list the inside the values collected.

I have some doubts regarding how to referentiate the tabless for "kind sensor"-"Sensors" wich columns should I put on the "sensor" table, also in this way I will get many tables. Do yo have any hint?

Answer 1

Simplest and easiest way to do it is to make all specific columns in your table "sensors" and have one foreign key to another table "sensor_type" which is consisted of 2 columns

table "sensor_type"
id_type  - identifier (primary key)
description - description of your sensor (heat, temperature sensor ... )

Your table sensor then looks like

table "sensor"
id_sensor                       identifier (primary key)
id_type                         foreign key references sensor_type table
size                            default null, if type 2 or 3 then something
weight                          default null, if type 1 and 3 then something
etc...

You need to understand this is probably one of many solutions which can solve your problem. I hope it helps.