BOM - I think how to do it in my database.
For example product1 include:A bill of materials or product structure (sometimes bill of material, BOM or associated list) is a list of the raw materials, sub-assemblies, intermediate assemblies, sub-components, parts and the quantities of each needed to manufacture an end product.
part1, 1pc
part2, 2pc
assembly1, 2pc
assembly2, 1 pc
Assembly 1 include:
part1, 2 pc
part3, 2 pc
assmebly3, 1 pc
Assembly2 iclude:
part4, 5 pc
Assembly3 include:
part1, 6 pc
part5, 2 pc
And at the finish i would like to have a list of parts(with quantity), that i need to product1. I'm talking about the structure of the tables - which will be the best? It can be assumed that the biggest level of complexity is 4 (sub - sub - sub - assemblies). Maybe one table [parts(also assemblies)] and one junction table[parts-parts] and big UNION query? Thanks for any help, the design of this structure is the key ...