For some kind of inventory system, a user can create a item_type which has certain properties, now the amount of properties is variable per type.. How should I go with the DBStructure on this? Just make a X amount of propertyX fields, or is there some other way to achieve flexibility in this way?
note I don't want to automaticly create tables, since that ain't managable.
The usual way to do this is like this (pseudo-SQL):
create table property_types (
property_id int primary key,
name varchar,
-- more info here
);
create table items (
item_id int primary key,
-- your item table
);
-- this table links a property value with an item
create table item_properties (
item_id int,
property_id int,
property_value varchar,
foreign key fk_item (item_id) references items (item_id),
foreign key fk_property (property_id) references properties (property_id)
);
Optionally, you can have a unique constraint on item_properties (item_id, property_id) to ensure that every property is set only once per item
Have a property table which is linked n:1 to the item_type table like this:
TABLE item_type (
item_type_id INT,
... )
TABLE properties (
property_id INT, -- primary key
item_type_id INT, -- foreign key for item_type
key NVARCHAR(max), -- adjust type to your needs
value NVARCHAR(max) )
So each item_type can have 0:n properties.
You could achieve a dynamic number of properties by creating a Properties table with each property referencing your Items table. e.g.
Items Table
Id Name
Properties Table
Id ItemId Name Value
In this manner, you're not limited to a static number of properties, or even the same properties. The Properties table would essentially be a dictionary table of name/value pairs with a strong tie to your Items table.
