Calculate "Expiration Date" Based on Date and Looked Up Value in MS SQL

I am creating an employee training tracking database. I have all of the training classes in a table along with the number of days said training is valid. (e.g. -[TrainingID],[TrainingName], [ExpirationDays]) I want to be able to have the expiration date automatically calculated when a user enters data into the training transactions table ([EmployeeID] foreign key, [TrainingID] foreign key, [TrainingDate] entered by user, [ExpirationDate] calculated based on [ExpirationDays] where TrainingID = currently entered TrainingID)