How to Implement Remote Validation in Mvc Using Sql Command

Hi I have develope an Asp.Net MVC web application,In my web app i want to implement remote validation to check username is already exists or not .I'm not Using Enity framework and I also read many blogs about remote validation most of them are using entity framework to do this method but i want to implement it in normal sql command.Any one please suggest any Model,Controller and view code and give some idea about it..