to connect with other database from Dynamics crm 2011 -urgent

Hi,

I want to fetch some value from other database from Case creation page in dynamics CRM 2011 and set a option type field which of bool type..

The actual scenario is on the case creation page there a text box when user key in there should be a method which should go and check it in a different database which on other server and on the basis of the result it should set a field on the case creation page..

Now I am unable to think which process to follow as how to connect with other database using script or have to write plugin and if yes what is the process of creation connection with other data base in plugin Or have to follow some other way...

please suggest...

Thanks