Data Mart - Connection Error

Based on the error message you provided, it seems that the login used to connect to the data mart is not authorized to access the data mart. To resolve this issue, you may try the following steps:

1. Check if the login used to connect to the data mart has the necessary permissions to access the data mart. In Azure Data Studio, you can use the Object Explorer to connect to the SQL Server instance and expand the Security folder to see the logins. You can then check the properties of the login to see its permissions.

2. If the login does not have the necessary permissions, you may need to add it to the appropriate security group or assign the necessary permissions to the login. This can be done using SQL Server Management Studio or T-SQL scripts.

3. Make sure that the server name, database name, and login credentials are correct. You can double-check these details in the Power BI service by going to the data mart settings and reviewing the connection details.

4. If you are using a firewall or VPN, make sure that the necessary ports are open and the VPN connection is established before connecting to the data mart in Azure Data Studio.

Once you have checked and corrected any potential issues, you should be able to connect to the data mart in Azure Data Studio without any issues.