You certainly can achieve such a thing via Oraclize!
First you'll need to create and expose and API to perform the database duties you need.
Next you'll need to use the Oraclize compuatation datasource in order to craft your post requests & payload data they might need. It involves creating a docker container containing whatever code it is you need to run, which you then deploy to the
Once done, you can run this code via an Oraclize query, passing along any data you might need in order to upate your database.
The Oraclize Examples Repo here has a "URL-Requests" example here that shows you how to do the above. There is also a Truffle Version of the example here, showing how you'd set it up in a development environment, with unit testing in place.