Oracle in a Nutshell

Associative Array

CREATE [OR REPLACE] TYPE type_name IS TABLE OF element_type [NOT NULL] 
        INDEX BY BINARY_INTEGER| PLS_INTEGER | VARCHAR2(n);

A singly-dimensioned, unbounded, sparse collection of homogeneous elements available only in PL/SQL, not in the database. Associative arrays can be indexed by a BINARY_INTEGER, a PLS_INTEGER, or a VARCHAR2.

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 may 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.

max_elements

Maximum number of elements for this associative array.

NOT NULL

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

BINARY_INTEGER | PLS_INTEGER | VARCHAR(n)

An associative array can be indexed by a BINARY_INTEGER, a PLS_INTEGER, or a VARCHAR value.