Is it possible to do it via SQL ?
It is probably very *possible*, but you shouldn't do that under normal circumstances. Use the built in APIs for working with content programmatically, or else you're going to end up in a mess with invalid or inconsistent content at some point. Remember there are all sorts of connections between content, content types, properties, property types, ACLs, relations between content and more. And to be sure everything in your system works as intended, all must be valid and correct.