Naming Conventions and Dual Approach to Database Operations

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As you study the functional organization of the FileManager methods, please keep this in mind: most of the common database operations (Open, Next, Previous, Fetch, Insert, and Update) come in two versions. The versions are easily identifiable based on their naming conventions:

 

Operation

Do Operation and handle any errors (automatic)

 

TryOperation

Do Operation but do not handle errors (manual)

Interactive Database Operations

When any of these methods are called (Open, Fetch, Next, Previous, Insert, and Update), they may take several approaches and several attempts to complete the requested operation, including issuing error messages where appropriate. These methods provide automatic error handling. They may solicit information from the end user in order to proceed with the requested task. They may even terminate the application under sufficient provocation. This means the programmer can rely on the fact that if the method returned, it worked.

Silent Database Operations

When any of these methods prepend "Try" (TryOpen, TryFetch, TryNext, TryPrevious, TryInsert, and TryUpdate), the method makes a single attempt to complete the requested operation, then returns a success or failure indicator to the calling procedure for it to handle accordingly. These methods require manual error handling.