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Oracle9i SQL Reference
Release 2 (9.2)

Part Number A96540-02
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TREAT

Syntax

treat::=

Text description of functions100.gif follows
Text description of treat


Purpose

TREAT changes the declared type of an expression.

You must have the EXECUTE object privilege on type to use this function.

Examples

The following statement uses the table oe.persons, which is created in "Substitutable Table and Column Examples". That table is based on the person_t type, which is created in "Type Hierarchy Example". The example retrieves the salary attribute of all people in the persons table, the value being null for instances of people that are not employees.

SELECT name, TREAT(VALUE(p) AS employee_t).salary salary 
   FROM persons p;

NAME                          SALARY
------------------------- ----------
Bob
Joe                           100000
Tim                             1000

You can use the TREAT function to create an index on the subtype attributes of a substitutable column. For an example, see "Indexing on Substitutable Columns: Examples".