Hello,
The recommended way to insert a new withdrawal using PHP is via the PHP API.
You also have the option to place a withdrawal via the JSON-API. If calling from the frontend, you can directly call the API. The login cookie in your browser will provide authentication. If you are calling from elsewhere, you need to have the user’s bearer token (you can get the bearer token from the user’s profile or from a get_nonces call while logged in with cookies. See the documentation for details.
If you want to directly insert a withdrawal into the DB you can also do this, but know that the SQL tables are going to be removed in wallets6, which will be out in a few months.
The PHP-API and JSON-API are currently being re-engineered for the new design and will remain, marked deprecated, for a long time, to allow a smooth transition to the new architecture. In fact, part of the reason that development is taking so long is because I am doing a test-driven re-development of these two APIs to ensure compatibility.
with regards