A lookup – or an external lookup (in technical terms, a left outer join) – refers to a database operation that links two database tables to form a view that combines data from both tables. In Monarch Classic, a lookup can be used to import fields into an existing Monarch Classic table, based upon a common link between the Monarch Classic table and an external database. For example, if the Monarch Classic table includes customer transactions along with a Customer ID field, you could use a lookup to import the customer name, address and other information for each transaction. The lookup would work by linking to an external database that contains the customer ID along with the customer information. See Working with External Lookups for additional information.