If a user is not willing to open up VNET-based connectivity to connect an on-premises database to Azure, there is an option to use Azure ExpressRoute.
Azure ExpressRoute is a private, dedicated, and high-speed network connection between an on-premises infrastructure and Azure data centers. ExpressRoute provides a more secure and reliable way to connect on-premises infrastructure to Azure compared to the public internet.
With ExpressRoute, you can establish a private and dedicated connection between your on-premises network and Azure through a service provider. This service provider can act as a bridge between your on-premises infrastructure and Azure, and allow you to access Azure services like Azure SQL Database or Azure Virtual Machines securely.
Using ExpressRoute, you can also establish a private peering connection between your on-premises network and Azure, which allows you to access Azure services without exposing them to the public internet. This provides an additional layer of security and ensures that your data remains protected.
In summary, Azure ExpressRoute provides a secure and reliable way to connect your on-premises infrastructure to Azure, without the need to open up VNET-based connectivity. It allows you to access Azure services through a private and dedicated connection, ensuring that your data remains secure and protected.