Oracle Application Software 10.1.3.4 Manuel d'utilisateur télécharger pdf (Page 162)

SQL Enhancements

D-4 Oracle Application Server Adapters for IMS/DB User's Guide

Accessing Hierarchical Data Using SQL

Data stored hierarchically in a IMS/DB data source can be referenced by using a

hyphen followed by a right arrow (->) to denote the parent child relationship in the

source:

FROM … parent_name->child1->child2… [alias]

Or, using an alias for the parent table:

FROM … parent_alias->child1->child2… [alias]

Flattening Hierarchical Data Using SQL

You can produce a flattened view of hierarchical data by embedding a SELECT

statement inside the list of columns to be retrieved by another SELECT statement. You

use parentheses to delimit the nesting. The nested SELECT statement can reference a

child rowset (using the parent->child syntax) only in its FROM clause.

Using an Alias

To list the hierarchical data with the parent data only, you must use an alias for the

child data.

Note: Without an alias the query lists, for each parent row, all of the

children of all of the parent rows.

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Oracle Application Software 10.1.3.4 Manuel d'utilisateur Page 162