17.00 - Example: A Simple Recursive View - Advanced SQL Engine - Teradata Database

Teradata Vantage™ - SQL Data Definition Language Syntax and Examples

Product
Advanced SQL Engine
Teradata Database
Release Number
17.00
Release Date
September 2020
Content Type
Programming Reference
Publication ID
B035-1144-170K
Language
English (United States)

This example uses the following base table as its base to build a simple recursive review definition with a counter to control the possibility of infinite recursion:

partlist
Part Subpart Quantity
00 01 5
00 05 3
01 02 2
01 03 3
01 04 4
02 05 7
02 06 6

This view is designed to answer questions such as the following: Which parts are required to build part 01?

Notice that as written, this query does not really answer the question because there might be more than 100 levels in the data. Strictly speaking, the question this request asks is this: Which parts, up to a maximum of 100 levels, are required to build part 01?

The recursive view definition is as follows:

    CREATE RECURSIVE VIEW rpl (part, subpart, quantity, depth) AS (
      SELECT root.part, root.subpart, root.quantity, 0 AS depth
      FROM partlist AS root
      WHERE root.part = '01'
    UNION ALL
      SELECT child.part, child.subpart, child.quantity, parent.depth + 1
      FROM rpl AS parent, partlist AS child
      WHERE parent.subpart = child.part
      AND   parent.depth <= 100);

The query to answer the question of which parts are required to build part 01 is the following SELECT request:

    SELECT part, subpart, quantity
    FROM rpl
    ORDER BY part, subpart, quantity;

The result set for this query is the following.

Part Subpart Quantity
   01    02    2
   01    03    3
   01    04    4
   02    05    7
   02    06    6