Example: Mutual Recursion - Advanced SQL Engine - Teradata Database

This example demonstrates mutual recursion, which is not supported for recursive view definitions.

Mutual recursion occurs when both of the following are true:

• Recursive view A invokes, either directly or indirectly, recursive view B.
• Recursive view B invokes, either directly or indirectly, recursive view A.

In the two mutually recursive view definitions provided here, the view named odd references the view named even, and vice versa.

    CREATE RECURSIVE VIEW even (n) AS (
      SELECT * 
      FROM (SELECT 0) AS a(i)
    UNION ALL
      SELECT m + 1
      FROM odd);
    CREATE RECURSIVE VIEW odd (m) AS (
      SELECT *
      FROM (SELECT 1) AS a(i)
    UNION ALL
      SELECT n + 1
      FROM even);