In order to get the data into a SQL database, you don't even need to store the submitted form in Laserfiche. In the Process Diagram add a Workflow Service Task.

Then create a workflow in Workflow that has its first activity using the "Retrieve Laserfiche Forms Content". Set it up to retrieve the field data you need from the correct Forms process. Depending on how your data is setup on the form (tables, collections, etc.) you may need to use other activities to parse through the different rows etc. being retrieved from Forms. Once you have that figured out, you can add a Custom Query activity or just a simple Insert Data activity to insert the data into a SQL database. Below is a screenshot of a Workflow diagram that does this:

Make sure after you save your workflow that you go back into the Forms process diagram and edit the Workflow Service Task so it has the correct workflow name.