Database Application Design

Characteristics of Database Applications

Form Design Report Design Application Program Design

Characteristics of Database Applications Object Materialization occurs when we

construct the objects using the underlying relations

Facilities for controlling processing include:– Commands– Menus– A Graphical User Interface

Characteristics of Database Applications (Cont.) An object view, or user view, is a named

subset of an object required by a specific user or user group.

Form Design

The form structure should reflect the object structure -> Fig. 8-8 and 8-2a

The semantics of the data should be graphically evident

The form structure should encourage appropriate action

Careful with cursor movement and pervasive keys

Form Design (Cont.)

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. 8-11– Check Boxes (more than one alternatives

may be chosen) -> Fig. 8-12

Report Design

Report structure: should reflect the structure of the underlying object.

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

Designing the structure of application logic: Pseudocode or other technique

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. 8-18 Other types of constraint checking e.g.

uniqueness