Database Application Design n Characteristics of Database Applications n Form Design n Report Design n Application Program Design

Characteristics of Database Applications n Object Materialization occurs when we construct the objects using the underlying relations n Facilities for controlling processing include: –Commands –Menus –A Graphical User Interface

Characteristics of Database Applications (Cont.) n An object view, or user view, is a named subset of an object required by a specific user or user group.

Form Design n The form structure should reflect the object structure -> Fig. 8-8 and 8-2a n The semantics of the data should be graphically evident n The form structure should encourage appropriate action n Careful with cursor movement and pervasive keys

Form Design (Cont.) n Forms in a GUI environment may include: –Drop-Down List Boxes -> Fig. 8-9 –Option or Radio Buttons (only one alternative can be selected) -> Fig –Check Boxes (more than one alternatives may be chosen) -> Fig. 8-12

Report Design n Report structure: should reflect the structure of the underlying object. n Implied Objects (Data sorting within a report) -> Fig. 8-13, 14 –Sorting by object identifier –Sorting by nonidentifier, nonobject columns –Sorting by attributes contained in object attributes

Application Program Design n Designing the structure of application logic: Pseudocode or other technique n Relationship constraint checking –Fragments: A row in a table which exists inappropriately without the required parent or child –Orphans: Child rows that exist without a mandatory parent

Application Program Design (Cont.) –Types of relationship constraint: Mandatory to mandatory Mandatory to optional Optional to optional –Restrictions on updates -> Fig n Other types of constraint checking e.g. uniqueness