How to create service principal, link to the azure sql database in the azure portal.

I want to know how to create service principal to connect to azure SQL server database.

(I tried by creating user assigned identity. But this also not succeeded.) The user assigned manage identity is configured by, *create user assigned manage identity and then assigned sql for azure services of that. *Then this USMI is assigned to both sql server and azure data factory including for owner roles and manage identity sections as well. But still coming following error.,

Error:

Cannot connect to SQL Database. Please contact SQL server team for further support. Server: 'servername came here', Database: 'db name came here', User: ''. Check the linked service configuration is correct, and make sure the SQL Database firewall allows the integration runtime to access.

Login failed for user '<token-identified principal>'., SqlErrorNumber=18456,Class=14,State=1,

Thanks