Sometimes you come across a problem in SQL that is far more complex than you first imagine. One classic of these is 'Relational Division' - a poorly understood aspect of SQL that can help answer what must be a common question:

Return the things that have all of the items in a given list

Example questions:

In this post I am going to look at Drupal Commerce and demonstrate how to prepare e-commerce product data for import into Drupal Commerce - and show how to create a delimited list of product references to link the products to their display nodes. These techniques supplement the wealth of great practical demos and documentation provided by the Commerce team.