My SP web application use FBA authentication (AD and aspnetSQLmembership providers). Requirement : I want the count of providers and display name for the provider.After that i want to check if user exist in more than one of the provider. How can i achieve this.
Is the requirement something that you are looking for in the People Picker? If so, the solution that's going to work out best for you is for a custom claims provider. With this, you can define exactly the criteria as specified in your requirements with your results appearing much like the normal search criteria does for the people picker.
Steve Peschka has an excellent article series on writing your own custom claims provider. It takes a little bit to digest, but as you go through and attempt to implement, you'll soon figure out the capabilities and how the flexibility of the claims provider will enable you to return the results you are looking for.
You have to do it manually via code for each provider and then make the count manually. For example: http://msdn.microsoft.com/en-us/library/ms152044.aspx