There are two options available
1. use the 'Import web service / XML file...' button in the toolbar of a Domain model
2. You could write a script in Typescript/JS that connects to the Model SDK. The script could map SQL to Entities in the Model SDK calls.
Some examples doing comparable things:
Mostly: nope. Since Mendix databases have some peculiarities like their own id-fields, you won't be able to import any database via any tool into a usable Mendix-database. You would need tricks to generate the Mendix-id's.
There is one option: importing an XML schema. the button is in the DomainModel view: "Import web service/XML file...". Might be useful for you if you can get an XML-schema.