Subtypes in Geodatabase)

(Original) subtypes in Geodatabase)
The two concerns of database organizations are integrity and efficiency. Fields and subclasses provide a way to organize data to ensure that these operations, such as editing, are more efficient while maintaining the integrity of attributes. The following describes the subclass issues.
An important decision for designing geodatabase is to determine whether to form a group of element classes or to establish a single element class with sub-classes. A subclass is a lightweight division of elements or objects in a element class or object class. The main reason for using subclass is to improve performance. Geodatabases with a few element classes have better performance than geodatabases with multiple element classes. Subclass allows you to specify a group of elements in a element class through attribute rules, relationship rules, default values, and connection rules. Whenever possible, you should first use sub-classes to distinguish the Associated Element groups.
Although all objects in a element class or table share the same behavior and attributes, not all objects share the same attribute domain. When an element class or an object in a table uses different attribute fields, objects in different attribute fields constitute the subtypes of the element class or table ). The word class of an object is determined by its subclass code value. The integer field of the subclass code is stored in the element class or table, each child type can have its own set of default values and attribute fields in a given field and associate them with different connection rules.
When designing Geodatabase, you need to decide where the Community and sub-types are used and where element classes need to be added, when you need to distinguish objects by default values, attribute fields, connection rules, and relationship rules, you need to create different child types for a single element class or table. When distinguishing objects based on different behaviors, attributes, access permissions, or multiple versions of objects, you must create another element class, that is, the associated element components must be divided into different elements: the associated elements of each group must be customized; the attribute of the element set is different; each element group requires different access permissions. Some elements need to be accessed by version, while others cannot.
Subclass provides a way to divide elements, that is, to divide element classes into multiple logical groups based on the value of long integer values. For example, a street class has a long integer attribute Field Class (street level). 1 indicates the main street, and 2 indicates the secondary Street. Divide the street class into two subcategories. The main street and secondary street are created based on the value of the column in the element class. Any element with a value of 1 is classified into secondary sub-classes. element classes with a value of 2 belong to primary sub-classes. In this way, you can use the symbol In ArcMap or edit it based on the subclass. Through the connection between a child and a domain, data integrity can be enhanced for the entire subclass.
Note: The subclass column must be a long integer. If data is imported from the info table to the Geodatabase table, only binary data items defined as 4 bytes are qualified. If there is no integer column, you need to create one. You can use the following technique: add a long integer column in Geodatabase, and then transfer the value in the original non-long integer column to the new integer column.
Reference
Development and Practice of ArcGIS 8 (Mao Feng)
Geodatabase tutorial (Training tutorial)
Building a Geodatabase (ESRI)