Designing a database

Designing a database involves four steps.

Decide what categories of information you work with. For example, you may have characters, starships, planets, and other categories. Each of these categories will become an object from which you'll create child objects.
Decide what properties each of your objects will contain. For example, an object representing a compact disc may consist of a name, an artist name, a picture of the cover art, any number of tracks, and other properties.
Decide, for each property, what type and other behaviors the property should have.
Analyze the tasks you perform repeatedly. Are there any additional tasks you want to perform with Ambry?

It's best to put your ideas on paper. List the categories you need and the properties for each category. An Adobe Acrobat file is included in the Documentation folder for you to use when designing a database.

Note that all objects have at least four properties in them. The Name property is a string containing the name of the object. The ID property is a number containing a numeric identifier, unique within a document, of the object. The Contents property is a placeholder for the object's content objects. Finally, the Parent property is a reference to the object's parent object, if any.

Object inheritance

When designing your database, keep in mind the concept of inheritance. You should plan to create objects as instances of other objects, rather than copying objects. Inheritance allows you to change an object's property definitions and have all instances of that object inherit that behavior.

For example, the CD Collection sample document defines two base objects, Compact Disc and Track. Each CD represented in the database is an instance of the Compact Disc object and each song in the CD's contents is an instance of the Track object.

Defining properties

Each property in an object consists of its name, the type of the property, and the property's data. When you define a property in an object, you need to determine what kind of data the property will store. There are currently seven property types in Ambry. For more information on using properties, see Editing objects in chapter five.

A simple property is the most commonly used and contains an unformatted string of up to 255 characters; the text can be displayed in one of several different ways as a string, as a decimal number, as a boolean true or false, or as a unit value from a specified unit set.

The data of a simple property can optionally be set by an expression or script and can be restricted to a particular range or to a specific set of values.

Use the simple property type for values such as an object's name.

An object list property contains a list of objects by default, all objects have a Contents property, but you can add other object list properties as desired. You can remove the default Contents property from objects for which having content objects is meaningless, such as the Track base object in the CD Collection database).

An object alias property contains a pointer to another object. All objects have a Parent property by default, which points to the object's parent. You cannot rename or delete the Parent property in objects.

A characteristics property contains a series of related boolean attributes. For example, the Compact Disc object in the CD Collection database uses a characteristics property to specify the genre of the music on the CD.

A text property contains any amount of unstyled text. If a property may often contain more than 255 characters, you should use this property type. A graphic property simply contains a picture. A sound property contains a sound, which you can then record into and play back.

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