As far as I know Strapi doesn’t support MSSQL but… if you want to use your existing MSSQL based framework + Strapi there is a workaround:
- install Strapi with --quickstart argument (it will create a Sqlite db)
- create the same schema in Strapi
- import your existing data into that db
- link Sqlite with MSSQL using an online tutorial like this one
From that point on you can use Strapi Admin UI to manage the data, to create new Web interfaces for it, while you will be abe to use the resulting data in your existing framework.
All the new data will be updated in your linked MSSQL server.
I didn’t test this setup, and I’m not an expert, if someone else knows a better solution I’ll be glad to hear it…