SQL Server 2017 and Azure SQL Database introduced native graph database capabilities used to model many-to-many relationships. The first implementation of SQL Graph introduced support for nodes to represent entities, edges to represent relationships and a new MATCH predicate to support graph pattern matching and traversal. We will be further expanding the graph database capabilities... Read more

https://blogs.msdn.microsoft.com/sqlserverstorageengine/2018/09/28/public-preview-of-graph-edge-constraints-on-sql-server-2019/