Understanding Entity Relationships in VB.NET

Printing QR Code in VB.NET Understanding Entity Relationships

An entity relationship in Microsoft Dynamics CRM defines how two entities interact with each other. A Microsoft Dynamics CRM entity relationship definition includes multiple parameters:

Relationship definition Specifies the nature of the data relationship between two entities (one-to-many, many-to-many, and so on) Relationship field Specifies the schema name and requirement level Relationship navigation Determines how the entity relationships should appear in the Microsoft Dynamics CRM user interface Relationship behavior Specifies the behavior between two entities, and how Microsoft Dynamics CRM uses that behavior to manage data when users take actions against one of the entities in the relationship Entity mapping Specifies how Microsoft Dynamics CRM maps common fields that two entities share

Microsoft Dynamics CRM includes hundreds of default entity relationships, and you can modify these default relationships or create entirely new entity relationships. You will almost always create at least one relationship between a custom entity and the Microsoft Dynamics CRM default system entities. In reality, you will probably create between 5 and 50 custom entity relationships for each custom entity that you create, depending on the complexity of your data model. Consequently, it s critical that you understand entity relationships before you create any custom entities.

entities, but you do need a thorough understanding of the different entity relationship types and the custom relationships that Microsoft Dynamics CRM supports.

You can view all of an entity s relationships by using the entity editor in Microsoft Dynamics CRM. Figure 9-1 shows some of the default entity relationships for the Lead entity.

This grid lists all the Lead entity relationships that Microsoft Dynamics CRM creates by default. To view the details of any one relationship, double-click a record in the grid. For example, double-click the record with the primary entity of Lead and the related entity of Contact, and you ll see the entity relationship editor shown in Figure 9-2. You can use the relationship editor to view and configure all of the entity relationship parameters. In the next subsections, we review each component of an entity relationship definition, starting with the data relationship.

One purpose of entity relationships is to define the data relationship between two entities in the system. Unlike a traditional database, in which you might configure primary and foreign keys to manage data relationships, you use entity relationships in Microsoft Dynamics CRM to manage how data interacts in the system metadata. This metadata design gives you the opportunity to customize and manage the data relationships easily without having to touch the underlying system data (and database keys) in Microsoft SQL Server. Microsoft Dynamics CRM uses three types of data relationships, which we review in more detail in the following sections:

One-to-many (abbreviated as 1:N) describes a relationship between two entities in which a single entity can possess multiple (many) related entities. For example, consider the relationship between the Account entity and the Contact entity in Microsoft Dynamics CRM. Each Account can have many Contacts, but you can assign only one Account to each Contact. As you browse through the Microsoft Dynamics CRM customization section, you might notice that the user interface uses different terminology interchangeably to describe the one-to-many data relationship, as shown in Table 9-1.

Although Microsoft Dynamics CRM uses different terminology to describe the one-to-many relationship, the user interface on an entity s form always displays one-to-many entities in a consistent manner. Figure 9-3 shows an example of the relationship between the Account and Contact entities of the Contact form. On the related entity s form (Contact), a lookup field labeled Parent Customer appears so that users can select the primary entity (Account).

Conversely, the related entity (Contact) does not appear on the form of the primary entity (Account). Rather, Microsoft Dynamics CRM adds a link in the navigation pane of the primary entity to a page that displays all of the related entities in a grid view, as shown in Figure 9-4.