Hi Ricky,
What is the AddressList you mention and what is the goal you need to achieve?
dbLookup functoid goes directly against the database you specify and returns data.
Each time it is called from within the XSLT transformation, it opens a connection, retrieves data, and returns it into XSLT.
It is not a good choice from perf point of view if multiple calls are expected to be performed; DB Operation element is a better one as it does a single hit against the database, however you may need more XSLT before/after.
Either way, hitting the database is the last resort, it is far better to go against BOs or any other kind of software-exposed interface.
For the dbLookup, if you need to apply a where clause, you need to build it using concatenation and feed it into the where clause of the dbLookup, I think – something like this.
Note – building SQL using string concatenation is error-prone, as it opens you for SQL injection.
Within DB Operation, when you build the SQL statement, you can use so-called safe links to the message data, which escape the value and wrap it safely for SQL.
Note that the table name for customer data in Epicor database is Erp.Customer.
The one without the schema (or, more correctly, dbo.Customer) is the view that only exists if there are UD Fields on the table and is joining the main table and the _UD one.
Mentioning this because I see Customer on your screenshot above.