Firstly consider whether inheritance is the best way to implement the behavior you need. Generally it is best to prefer composition over inheritance. From your diagram I'd say that you really don't need inheritance at all to solve your problem.
If you do need to implement inheritance then there are a number of strategies you can use. It is a really good idea to look for an object relational mapper as a good one can make implementing the below strategies much easier. If your using .NET then NHibernate or Entity Framework are good options. For Java Hibernate is pretty good.
Table per class hierarchy
Here you'd create a single table for the entire class hierarchy. This makes most sense
when the classes in the hierarchy all share many columns. You'd need to add a "discriminator" column so you could identify which subclass each row belongs to. In your example you'd have
I'd say this strategy makes most sense for you as there don't appear to be many different columns between your sub-classes.
Table per subclass
In this example you'd create a table for each subclass. This makes most sense when the classes in the inheritance hierarchy don't share many common columns.
So you'd have tables like this:
- product_gallery
- logbook_galleries
- product_picture
- logbook_picture
Table per class
This is the strategy from your diagram. Like table per-subclass, This is useful when each of the sub-classes has different columns. The advantage over table-per-subclass is that it is easier to query the entire class hierarchy in one big join, the disadvantage is that you end up with lots of tables.
