I dont seem to find a way to write the output from a previous step in the flow into a SQL table, using the SQL recipes. When I read the documentation, it seems both types of SQL action can only take as an input a SQL dataset? This cant be write, as you would imagine you would want to create datasets in the flow and then commit them to a database?
https://doc.dataiku.com/dss/latest/code_recipes/sql.html
In the docs above, it describes In\Out parameters as needing to be SQL.
Indeed, it doesn't seem possible with a SQL recipe which executes fully in the database.
That being said you can probably use a sync recipe to put your non-SQL dataset in your SQL db so that you can execute a SQL recipe.