Oracle 8i and 9i PL/SQL Collections and Records

Collections in SQL

Nesting

MULTISET

Unnesting (TABLE operator)

COLUMN_VALUE

Implicit Joins and Outer Joins


	Nesting is all about getting relational or flat data into a collection.
	MULTISET used in nesting to convert relational data into collection, usually a collection of objects. Since more than one result set is not allowed inside CAST, MULTISET tells Oracle to treat the multiple-row result set as ONE collection.

	Unnesting is all about getting collection data out into a relational or flat form to be viewed or manipulated.

	COLUMN_VALUE is the “hidden” name of the column where your values are stored in a scalar collection with no attributes. Collections of objects or records have named attributes for every field, and therefore do not need the COLUMN_VALUE column name to access data.

	CAST doc