Working with Salesforce relationships is a little different from traditional relational database structures, but Salesforce has great tools for building custom data relationships and most people can adapt quickly to the SOQL model. As with any other system, though, there are a few "gotchas" to watch for when designing Salesforce relationships. I ran into one of these gotchas just recently. I needed a lookup relationship from our custom object to the standard Product table, Product2. No problem, right? Create the lookup field in the custom table, and there it is. Not so fast!