with recursive (non-linear)

Referencing the query_name more than once in the query definition:

WITH RECURSIVE query_name (c) AS (
   VALUES (1)
   UNION
   SELECT x FROM query_name JOIN base_table
                              ON base_table.x = query_name.c
   UNION
   SELECT y FROM query_name JOIN base_table
                              ON base_table.y = query_name.c
)
SELECT *
  FROM query_name

Related

• Tutorial: With — Organize Complex Queries

• Other forms: cycle … set … to … default … using, with, with recursive, with in subquery, with recursive in subquery.

• Product specific forms: connect by.

Normative References

The with recursive clause is defined in ISO/IEC 9075-2:2023 §7.17 as part of optional feature T131, “Recursive query” but non-linear recursion is prohibited in ISO/IEC 9075-2:2023 §7.17 SR 3jx.