MS Dynamics Entity Relationship

An entity relationship in Microsoft Dynamics CRM defines how two entities interact with each other.
Microsoft Dynamics CRM uses three types of data relationships, which we review in more detail in the following sections:
Hierarchical Relationships - 1:N and N:1

One-to-many (1:N) - relationship between two entities in which a single entity can possess multiple (many) related entities. For Example, Each Account can have many Contacts, but you can assign only one Account to each Contact.

Many-to-one (N:1)

MS Dynamics CRM Web Resources

Web resources are virtual files that are stored in the CRM database and that you can retrieve by using a unique URL address. Solution -> Entities -> Web Resource

Limitations of Web Resources
Web resource does not supports ASP.NET(.aspx or asmx) page to execute code on the server. Web resources are either static files or files with code that is processed client-side by the browser.

Web resources are only available by using the CRM web application security context. Only licensed CRM users who have the necessary privileges can access them.

Size Limitations - The maximum size of files that can be uploaded is determined by the Organization.MaxUploadFileSize property.
Settings -> System -> Administration -> System Settings -> E-mail tab -> Maximum file size (default 5 mb). This setting limits the size of files that can be attached to email messages, notes, and web resources.
Web Resource Properties - Name, Display Name, Description, Type, Language