This is more of a comment, but since this is a lengthy response that's worth mentioning, I'm posting it as an answer.
Your database looks sufficient for your needs. (Well, as best can be assumed from the diagram.) I assume that the
UserAccount table has a one-to-many relationship between the four tables
Movie (from here on, the V-B-V-M tables.) Next, I assume that the
Asset table has a one-to-one relationship with each link between the V-B-V-M table entries. With this information, I would recommend moving the
UserAccount_id from each V-B-V-M table, to the
Next, it seems that
Asset is always associated with one of the four V-B-V-M tables. Considering this type of setup, I would recommend creating an additional table--
| AssetType |
| id |
| typeDesc |
Next, update the
Asset table and each V-B-V-M tables to include a
AssetType_ID field. the
AssetType table should include one entry, for each type of asset. In this case,
Video Game and
Movie, each with a unique description and ID.
You may want to do this for a couple reasons-- First, you can now query the
Asset table and discern what type of asset is stored in a specific record, without having to link the data to your four other V-B-V-M tables. This will speed up your querying of the data, when all of the information from your four tables isn't needed. Second, this also provides an easy means of linking in a textual description of the type of asset associated with the
Asset entry. Again, without having to link to the V-B-V-M tables to figure that out.
Last, you may want to consider handling the barcode data differently. If barcode is a simple look-up, you can add it to the asset table. However, if barcode values have to be unique, keeping it in a secondary table is necessary because you'd have to put a constraint on the database. You could do this if it was integrated in the
Asset table, however, your vehicle data would cause problems because vehicles do not have barcodes. To my knowledge most, if not all, major database engines won't allow you to define a unique field, that also allows
null values because, then, the data is no longer unique.
You might be inclined to think that you could combine the
Barcode field with the
VIN. Since VINs are unique and Barcodes are unique, and neither should be the same, why can't they be combined into one field on the
Asset table, which allow you to drop the additional
Barcode table. I wouldn't recommend this because I think it gives the data less "focus".
Yes, it is a form of unique object ID but barcodes are barcodes and VINs are VINs-- the concept behind both is completely different and consolidating the two can become confusing with time. Furthermore, if you expand your project in the future, it could cause collisions. Technically, I don't see a big problem with that (in your case) but I'd still highly recommend avoiding that option.
Also, I would also add the
assetType_id to the
Barcode table, for the same reasons you added it to the