Which Azure CLI command is used to create a SQL Database server?

The Azure CLI command used to create a SQL Database server is "az sql server create." This command is specifically designed to establish a new SQL server instance in Azure, which acts as a container for your SQL databases.

When you execute the command, you need to specify parameters such as the server name, resource group, location, administrator login, and password. This proper setup allows for the management of multiple databases under one server instance, which is a key aspect of Azure SQL Database architecture.

The other options are not correct because they refer to different functionalities. For example, "az sql database create" is intended for creating a database within an existing SQL server, not for creating the server itself. "Az sql server add" does not exist in the context of Azure CLI and operates under incorrect syntax or misunderstanding. Lastly, "az database create" is also not valid; there’s no such command in Azure CLI for creating a database server. Therefore, "az sql server create" is the only correct command for this particular action in Azure.