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SQL Optimizer for DB2 ZOS 5.6.1 - Release Notes

QB

Auxiliary node that represents a subquery in a particular SQL statement.

A subquery can be any of the following operations:

  • MERGE
  • INSERT
  • SELECT
  • UPDATE
  • DELETE
  • SELECT with FOR UPDATE OF
  • UPDATE WHERE CURRENT OF CURSOR
  • DELETE WHERE CURRENT OF CURSOR
  • TRUNCATE
  • Table expression
  • Correlated subselect or full select
  • Non-correlated subselect or fullselect
  • EXCEPT
  • EXCEPT ALL
  • EXCEPT
  • EXCEPT ALL
  • UNION
  • UNION ALL

Notes:

  • The query block node is the root of a subtree and represents the whole subquery.
  • QBn denotes a query block node,where n represents the query block number.

 

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