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Recursion in SQL. SQL2 had no recursion. You can find Bart’s parents, grandparents, great grandparents, etc. SELECT p1.parent AS grandparent FROM Parent p1, Parent p2 WHERE p1.child = p2.parent AND p2.child = 'Bart'; But you cannot find all his ancestors with a single query. SQL3 introduces recursion. WITH clause.
Recursion in SQL. SQL2 had no recursion. You can find Bart’s parents, grandparents, great grandparents, etc. SELECT p1.parent AS grandparent FROM Parent p1, Parent p2 WHERE p1.child = p2.parent AND p2.child = 'Bart'; But you cannot find all his ancestors with a single query. SQL3 introduces recursion. WITH clause.
Introduction. Example schema: ParentChild(parent, child) Example data: (’Homer’, ’Bart’); (’Homer’, ’Lisa’); (’Marge’, ’Bart’); (’Marge’, ’Lisa’); (’Abe’, ’Homer’); (’Ape’, ’Abe’); Example query: find all of Bart’s ancestors. “Ancestor” has a recursive definition: SQL2 does not support recursive queries:
SQL Recursion WITH stu that lo oks lik e Datalog rules an SQL query ab out EDB, IDB Rule = [RECURSIVE] R ( < argumen ts > ) AS SQL query 1. Example Find Sally's cousins, using EDB Par(child, parent) .
Data provenance for recursive SQL queries. We propose to bank on data provenance as one tool that can provide insight into recursive query computation. Here, we focus on where- and why-provenance [3, 12] derived at the level of individual table cells. We aim to derive •where-provenance which identifies those table cells that were
20 Φεβ 2019 · One way to accomplish this is with a SQL feature called recursive queries. Let's take a real-life example. Let's assume we've got a database with a list of nodes and a list of links between them (you can think of them as cities and roads). Our task is to find the shortest path from node 1 to node 6.
Example API: Python. psycopg2.
