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OpenEdge Development: AppBuilder
Introduction : Anatomy of a database application
 
Anatomy of a database application
Although each application differs greatly in detail, there is an underlying framework that can be represented as:
*Finding certain records in a database.
*Displaying them.
*Modifying them.
*Updating the records in the database.
Finding records involves opening a database file and searching through it for records that have certain characteristics. The desired characteristics are defined in a query. A query might be as simple as “get all records” or highly complex, involving comparisons on many different fields in a multitude of records.
Records returned by a query can be displayed in tabular format for easy browsing, formatted in a more complex way suitable for editing, or used to generate, for example, mailing labels.
Modifying a record is a simple clerical process on one level. But because humans are involved, mistakes are virtually guaranteed to occur. A careful developer will account for this fact and take steps to check the changes being made, insofar as checking is practical.
Once changes have been made, the modified records must be written back to the database. This can be done immediately, for simple updates, or buffered to a staging area as part of a more complex transaction process.
AppBuilder supports objects that address all four steps in this framework.