Lookup controls include an editable field and a lookup push button. The following illustration shows the salesperson lookup control. When the user clicks the lookup button, the Salesperson lookup window will appear:
Most lookup fields are a key for a table, such as a salesperson ID, a customer ID or a document number. The lookup button’s change script displays a lookup window listing all the records associated with the lookup field. When the user selects a record and the lookup window closes, the lookup window returns the value to the lookup field.
Two types of lookup controls are used in a primary window: primary lookups and secondary lookups.
The primary lookup is the first lookup control on a window. This lookup control should allow the user to view records entered and maintained in the current window (such as master records entered in a maintenance window).
You should never disable a primary lookup button, but you should lock the lookup field. This includes times when the user adds a new, unsaved record or when the user retrieves an existing record.
Secondary lookups display related records (such as checkbook, salesperson or class IDs related to a customer record) and associate them with the record displayed in the current window.
Secondary lookup controls work similarly to a primary lookup; however, secondary lookup fields should provide the ability to zoom to a maintenance form and display the entire record, and should allow the user to add records on the fly.