Oracle in a Nutshell

Nested Table

[CREATE [OR REPLACE]] TYPE type_name IS TABLE OF element_type [NOT NULL];

A singly dimensioned, unbounded collection of homogeneous elements available in both PL/SQL and the database as a column or a table. Nested tables are initially dense (they have consecutive subscripts) but can become sparse as a result of deletions.

Keywords

type_name

Any valid identifier that will be used later to declare the collection.

element_type

Type of the collection’s elements. All elements are of a single type, which can be most scalar datatypes, an object type, or a REF object type. If the elements are objects, the object type itself cannot have an attribute that is a collection. Explicitly disallowed collection datatypes are BOOLEAN, NCHAR, NCLOB, NVARCHAR2, REF CURSOR, TABLE, and VARRAY.

NOT NULL

Indicates that a collection of this type cannot have any NULL elements. However, the collection can be atomically NULL (uninitialized).