SQL Optimizer for DB2 ZOS 5.6.2 - User Guide

UNION

Combine rows from multiple tables and remove duplicate rows.

A UNION construct contains a UNION node and at least one subtree. Each subtree contains a WFSCAN node, a WORKFILE node, a SORT node, and the source query block node.

UNIONA

Combine rows from multiple tables and retain duplicate rows.

An UNION ALL construct contains a UNIONA node and at least one subtree. Subtrees denote any source query blocks.

UPDATE

Modify rows in a table.

An update construct contains one UPDATE node and one of the following: single-index access, multiple-index access construct, or table space scan.

UPDCUR

Represents UPDATE WHERE CURRENT OF CURSOR value.