Purpose of SQL Server Application Roles I've been reading up on application roles in Microsoft SQL server. It seems an application role is like any other role in that permissions on securables can be granted to an application role, however, the difference being that it has to be "called" by an application using the stored procedure sp_setapprole.

The only reason I can see for using this is for a DBA to allow an application (and its developers) to connect to the database and not having to supply a server login or a database user and therefore the developers cannot connect directly to SQL Server (via SSMS for example) even then, I can't really see a benefit to this as surely the account provided to the application / developers would be granted the minimum required permissions anyway?

Am I missing something here?
Application roles do not eliminate the need to supply initial connection credentials. One must first successfully authenticate to the server/database using a login (SQL or Windows account/group), or contained database user) before an application role can be activated. 

Application roles mostly differ from regular database roles in that they:


have no members
are enabled using sp_setapprole with the app role password after successful authentication
are unset using sp_unsetapprole with the cookie returned by sp_setapprole (required for connection pooling)


There is no value in using an application role when a service account (with the permissions needed by the application) is used for application database access. 

A use case for application roles is when users connect to SQL Server from the application using their own security credentials (e.g. Windows authentication via Windows group membership) but do not have the permissions the application requires. Activating an application role in this scenario allows auditing of individual user activity (e.g. using ORIGINAL_LOGIN()) without granting permissions beyond CONNECT, although users could be granted permissions for needs outside the application, such as those needed for a reporting tool. This would allow read-only access for reporting while limiting writes via the application.