Reading time ~6 minutes Querying hierarchical data is always where the big boys of SQL shined. And I really mean the big boys part since only Oracle, and Microsoft SQL Server have support for CTE (Common Table Expressions) that allow for executing one SQL statement what will fetch a subtree. There are data modeling approaches that allow for doing hierarchical data reads with noSQL databases and databases without support for CTE. The most common and obvious example of hierarchical data is the family tr...