unable to connect sql server with salesforce directly using API's. Using Http API we can connect to sql, but please any one confirm that sql server is having webservice api's or not?? I want to write an apex class where i want to use Http(rest api) and integrate with salesforce but i can't due to unavailability of sql server http api.
As far as I know:
SQL don't have such type of interface or web-service in built. But there are two ways you can achieve Salesforce integration with SQL DB
Develop your own interface. A web-service implemented on windows or other instance which can work as an Interface between SQL and Salesforce. Interface can have some exposed service URLs which can perform operation for you. This type of approach has been implemented several places using .NET and other technologies.
Next approach is install some SQL connectors/adapters available in market. But they are all paid, provide that required interface for you.
In most scenarios "Jitterbit" tool is used.