Oracle XML DB is easily installed using either the Database Configuration Assistant (DBCA) or by running a catalog script,
The XML DB product provides all the features discussed in this article.
Another special type is the VARRAY or varying array type.
The implementation of these standards in Oracle allows us to look inside an XML document in ways that were not possible in older SQL standards. A new datatype, XMLType, was introduced in Oracle9 Database Release 1 to allow an XML document in the database to be accessible in SQL and at the same time allow XML developers the ability to use XML standards on a document.
Population of a varray type is identical to population of a nested table type with the exception that you can only insert up to the maximum specified count of the varray.
Use of Other Built-in Methods for Collections In addition to the constructor type Oracle also provides collection methods for use with VARRAYS and nested tables. Collection methods cannot be used in DML but only in procedural statements.
Use the FIRST and NEXT collection methods to transverse these null values. First, we use the FIRST collection method to get the index integer of the first valid record for the dependents nested table.
Remember that a nested table is a sparse construct so the first valid value may not be one.