Microsoft®’s popular relational database management system, SQL Server®, is available in multiple editions with features and licensing options intended to appeal to a wide range of users. The most common editions and licensing requirements are summarized below:
SQL Server 2016 Enterprise
The Enterprise edition may only be licensed on a per-core basis. Microsoft requires a minimum of four core licenses for each physical processor on the server. Additional licenses may be purchased in pairs. Users are not required to purchase Device or User CALs with core based licensing, making it the ideal solution for environments where the number of users or devices is particularly large or unknown.
SQL Server 2016 Standard
The Standard edition may be licensed on either a Server plus CAL basis, or per core, as with the Enterprise edition. Server plus CAL licensing requires a SQL Server license for each server running SQL software plus a User or Device CAL for each user or device accessing the server(s). Each SQL Server CAL allows access to multiple licensed SQL Servers. This is often the preferred model for organizations that know the number of users or devices, but core-based licensing is available on Standard edition for those who do not.
As is typically the case with Microsoft, the Enterprise Edition of SQL Server 2016 includes added features and functionality which are not offered on the Standard edition. The most notable differences are Advanced Corporate Business Intelligence (BI), Data Enterprise Management, Advanced Security, and In-memory ColumnStore and In-memory OLTP.
SQL Server 2016 may be licensed in virtual environments in much the same manner as physical OSEs. For further information on licensing within virtual environments as well as additional licensing options and considerations, I recommend the Microsoft SQL Server 2016 Licensing Guide.