The wikipedia defintion of a graph databases is " In computing, a graph database is a database that uses graph structures for semantic queries with nodes, edges and properties to represent and store data. A key concept of the system is the graph (or edge or relationship), which directly relates data items in the store. "
An introductions to graph databases from a Neo4J viewpoint is described.
There a a couple of UK based training conferences specifically for Graph databases
GraphConnect a leading conference for Neo4J , 11 May 2017 this year
Connected Data London has no date yet for this year. Last year's presentations for the conference are available free online to view. One talk is "Using RDF and graph technologies at NASA" talk by David Meza, Head of Knowledge Management at NASA is shared.
There is graph support in the next version of SQL Server. The private preview pages states
SQL Graph adds graph processing capabilities to SQL Server, which will help you link different pieces of connected data to help gather powerful insights and increase operational agility. Graphs are well suited for applications where relationships are important, such as fraud detection, risk management, social networks, recommendation engines, predictive analysis, dependence analysis, IoT suites, etc.
Initially,SQL Server will support CRUD graph operations and multi-hop graph navigation, and thefollowing functionality will be available in the private preview:
Create graph objects, that is, nodes to represent entities and edges to represent relationships between any 2 given nodes. Both Nodes and Edges can have properties associated to them. SQL language extensions to support join free, pattern matching queries for multi-hop navigationKennie Pontoppipidan wrote a great blog post on where to find out more information.