Yes its true but want to use as SQL Hosting Provider 

Your hosting provider will need to give you a static IP address for the SQL instance so that you can manage the DNS as I mentioned, or the provider will need to managed the DNS for you.  What SQL hosting provider are you using?

How to create a dns record to connect sql from any where from internet using name instead of IP address. like 

sqlsrv.mydomain.com or sql.myhosti

Check this link...

http://blogs.msdn.com/b/dbrowne/archive/2012/05/21/how-to-add-a-hostname-alias-for-a-sql-server-instance.aspx

http://geekswithblogs.net/twickers/archive/2009/12/08/136830.aspx

This really isn't a SQL Server question. Domain name registrars can register a domain name and often provide DNS services too.  You will need a static IP address for the DNS.  Search the internet for "domain name registration". 

Exposing a database server to the public internet isn't generally a good idea.  Be sure the server is hardened.

Yes its true but want to use as SQL Hosting Provider