1. The Business of IT ® www.parivedasolutions.com Austin Code Camp ‘08 Prescriptive Data Access Development in.NET 3.5 Austin, TX May 17, 2008 Brian Orrell brian.orrell@parivedasolutions.com http://borrell.parivedasolutions.com/ * For Internal Use Only *

2. DRAFT: For Discussion Purposes Only 2 Many times simple CRUD features seem like no-brainers and their user stories are not given the same amount of forethought and planning as other features of a system ► What are the auditing requirements of the system? Do you need to know every change that has been made to a record? What information needs to be saved for auditing records? ► What type of concurrency should be supported? If a user changes data after a page has loaded but before it is saved, what should happen? If data is deleted on one system while being viewed on another, what should happen when an edit is attempted to be saved? ► What type of transactional integrity is required by the different entities? Can an invoice live without children? Can a customer that has many addresses be entered without at least one? ► Where type of data validation is required for the fields of the entity? Where should the validation live? What should be the method for displaying validation issues? ► How should successful and unsuccessful save operations be communicated? When an insert is successful, where the user be taken? When a delete occurs, what should happen? When an update occurs, should the user remain on the newly updated record?

3. DRAFT: For Discussion Purposes Only LINQ to SQL provides a consistent and extensible approach to managing the not-so-simple tasks involved in day-to-day CRUD development ► Supports multiple ways to handle optimistic concurrency (Serves as a good base framework to apply even if you’re not using LINQ to SQL) ► Will not update the database when no “true” changes have occurred on the UI (Uses a variation on the observer pattern that identifies the real changes that should be made to the system) ► Extensible platform for inserting auditing and other logic at the business logic layer (This is the crux of what will go in a LINQ data layer) 3

4. DRAFT: For Discussion Purposes Only Let’s build the application… 4

5. DRAFT: For Discussion Purposes Only Best practices for using LINQ to SQL for Data Access Applications ► Use a Timestamp (Version) column whenever possible to ensure proper and performant concurrency checks ► Always trap for ChangeConflictExceptions when submitting changes to the database ► Form and DetailViews are evil… avoid them like the plague ► Do not use Attach using a new entity unless you are maintaining the original values of all the values you are changing ► Only use Attach(entity, original) if you are not using a versioning column in your entity ► Only use Attach(entity, true) if You are using a versioning column You are using a serialized or full-object graph of your entity ► Test, Test and Test again ► NEVER pass DataContexts around and always surround them with using statements 5