No, you cannot activate Remote Desktop Services (RDS) User Client Access Licenses (CALs) for Windows Server on SQL Server. RDS CALs are used to enable remote access to Windows Server desktops and applications, allowing users to access them remotely. On the other hand, SQL Server is a database management system, and it does not utilize RDS CALs for remote access.
RDS CALs are separate licenses that need to be purchased and activated on the Windows Server that is running the Remote Desktop Services role. These licenses are not applicable to SQL Server or any other software product.
If you are looking to enable remote access to a SQL Server database, you can use the appropriate client software or technologies such as SQL Server Management Studio (SSMS) or programming languages that support connecting to SQL Server databases remotely. However, accessing SQL Server remotely does not involve RDS CALs.