SQL Server 2017 Graph Database an Overview

A graph database is a collection of nodes (or vertices) and edges (or relationships).

A node represents an entity (for example, a person or an organization) and an edge represents a relationship between the two nodes that it connects (for example, likes or friends). 

Both nodes and edges may have properties associated with them.

Main features:

• A single edge can flexibly connect multiple nodes in a Graph Database
• We can express pattern matching and multi-hop navigation queries easily

When to use a graph database?: 

• When we have Hierarchical data
• When we have Complex many to many relationships

We can achieve similar behavior using Relational database also.

Other vendors providing graph database functionality:

• Neo4j
• mongoDB
• Oracle etc. 

Where is it used?

• Recommendations on online shopping sites
• Social networking sites to find your first or second connection
• Portfolio analysis

What are the components of graph database?

• Node - Consists of properties
  It creates $node_Id columns to uniquely identify each row
• Edge - Connects two or more edge, it may or may not have properties
  It creates following columns:
  
  $edge_Id - to uniquely identify edge
  $from_Id - Unique Id of node
  $to_Id - Unique Id of node 

Example:

Problem scenario: Find organization hierarchy of a person

Using recursive CTE:

And perform pivot operation to get data on columns 

Using graph database:

Power Bi visualization of graph using Force-Directed Graph: