Where to write add/edit/insert statements?

I created a custom target, which is an external database. Further, I configured some entitlements which are requestable from the IT Shop. A user will request these entitlements, it will go thru an approval and finally get approved. Upon approval I want to write 'INSERT' sql statement to assign appropriate entitlement to the user (in the target system), where should I write this code? Similarly I want to write DELETE stmt to remove entitlement. I'm new to this tool, please be more specific in your details. Thanks.