Oracle C++ Call Interface Programmer's Guide

Overview of Metadata
Overview of Metadata
Database objects have various attributes that describe them, and you obtain
information about a particular schema object by performing a DESCRIBE operation
for the object. The result can be accessed as an object of the Metadata class in that
you can use class methods to get the actual values of an object. You accomplish this
by passing object attributes as arguments to the various methods of the Metadata
class.
You can perform an explicit DESCRIBE operation on the database as a whole, on the
types and properties of the columns contained in a ResultSet class or on any of
the following schema and subschema objects:
■ Tables
■ Views
■ Procedures
■ Functions
■ Packages
■ Types
■ Type Attributes
■ Type Methods
■ Collections
■ Synonyms
■ Sequences
■ Columns
■ Argument
■ Results
■ Lists
You must specify the type of the attribute you are looking for. By using the
getAttributeCount, getAttributeId, and getAttributeType methods of
the MetaData class, you can scan through each available attribute.
All DESCRIBE information is cached until the last reference to it is deleted. Users
are in this way prevented from accidentally trying to access DESCRIBE information
that is already freed.
6-2 Oracle C++ Call Interface Programmer’s Guide