Hello Aayush,
The web designer is not able to connect to a database in a way you describe. There is another approach how to solve this.
You can use process variables. You can fill the Actors field in designer with a value like #{actors}. In your code, you can fetch data from a database and supply them as a process variable "actors" to a process instance when calling startProcess() method.
See also: https://community.jboss.org/thread/216207
Hope that helps.