Hello. This is my first post. I'm from Spain.
I want to develop an app for catalog library items. I know there are some models but I want one specific and I would like whether somebody can help me or not.

I would like, at first, to have visual elements, like 2: a collection of images and a collection of videos.

I want to have multimedia elements, that consist on a pack (a music item) and a visual (video) element (the category we did before).

Can somebody help me??? Thanks

Let's step back and get a "bigger perspective" so that we solve a problem instead of dealing with a very small task.

Ignoring the computer aspects for the moment, what real world problem are you trying to solve? In other words, what is the purpose for creating this model?

What tools will you be using to manage this model? While the concepts are the same, the practical aspects vary tremendously between CICS and DB2 on zOS, PHP and MySQL on Linux, ASP and MS-SQL on Windows, and Eclipse and SQL-Lite on Android. The data itself needs to stay abstract and platform independant, but there are design aspects that do influence some schema design decisions in important ways that make life significantly easier for a beginning developer.

-PatP

OK. Thanks for the answer.
What I'm trying to do is an entity-retationship diagram to achieve this.
The program will use a h2database (relational DB) and will be for Windows.
Anyway, what I would like is an entity-relationship to know where I can begin.

I guess that I'm not asking the correct question... I'm trying to figure out how to help you.

Let's approach the problem a different way. What do you know about data modeling and ER diagrams now? How will having an ER diagram help you with your project?

I'm trying to understand what you need so that I can help you get there. I've never heard of anyone that starts a project with an ER diagram. You need to do a lot of other things first, so instead of pluning into creating an ER diagram that may or may not help you I'm trying to figure out what I can do to help you.

-PatP

OK. Let's try again. Sorry but my English is not very good and it's difficult for me to explain.
I'll explain everything.

I'm a software developer that want to make a database program (h2database, so SQL Db.).

I want to catalog 4 types of elements of a library, but in the future perhaps I will add some more.
At this moment, I will catalog 4 types:

Type 1) writing elements as books collections (several collections of books), individual books (books that aren't in any collection), magazines and newspapers).

Type 2) Sound elements, consist on Tapes (one or several), disks (one or several), and mp3 (one or several).

Type 3) Visual elements as Collections of images and Collections of videos.

Type 4) Multimedia elements consist on packs (1 Visual element + 1 Sound element).

With this data I would like to develop the entity-relationship diagram, because the interface will simple, but I don't know where begin.
I suppose I must maintain a first table named Library for instance. This table will be the parent of 4 child tables (relation ISA) with these 4 tables named "Writings", "sounds", Visuals" and "multimedia".
The problem begins when for instance, Visual Elements must link with Collections of images and videos. Must I create a table Collections, or must I create Tables Images and Videos, and afterwards link with Visuals table by using intermediate tables (relationships tables). I think is the last one because images and videos will have different fields.

Because I have a lot of problems, is why I want to have entity-relationship diagram so I can view graphically how to achieve this.
I'm beginning with databases , and I will learn by making this program. I'm learning a lot by reading dbforums post, but I want to make my own program.