SQL server authentication is used to allow access to specific user to connect with authorized database with set privileges. While installation if you have selected windows authentication mode and now you want to change it to SQL Server and windows authentication so you can enable this by following the steps given in the article that how to enable SQL Server and windows authentication instance.
Enabling SQL Server and Windows Authentication using SQL Management Studio
For enabling SQL Server Authentication with windows authentication in your MSSQL instance (default instances are usually MSSQLSERVER/MSSQLEXRESS):
Open “SQL Server Management Studio“.
Connect to SQL Server instance you would like to enable for dual mode authentication.
Right-click the server instance name from the object explorer, and then click on “Properties” to open server properties window.
In the left pane, select “Security“.
From the right pane Select “SQL Server and Windows Authentication mode” radio button that is under the Server authentication section to enable and then click “OK“.
Right-click the server instance name from the object explorer, and then click Restart (it will restart MSSQL Server service). Or you can restart it from services. (If the SQL Server Agent service is running, you need to restart it too)
Hope this Helps!
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