Chapter 7. Application Selector Layer

Apex is a very expressive language to perform calculations and transformations of data entered by the user or records read from your Custom Objects. However, SOQL also holds within it a great deal of expressiveness to select, filter, and aggregate information without having to resort to Apex. SOQL is also a powerful way to traverse relationships (up to five levels) in one statement, which would otherwise leave developers in other platforms performing several queries.

Quite often, the same or similar SOQL statements are required in different execution contexts and business logic scenarios throughout an application. Performing these queries inline as and when needed can rapidly become a maintenance problem as you extend and adapt your object schema, fields, and relationships. Salesforce also requires through its Security Review that object and field level security be enforced in code, thus further burdening inline queries with additional boilerplating...