Tài liệu PL/SQL User’s Guide and Reference phần 3

Defining and Declaring Collections
To create collections, you define a collection type, then declare collections of that
type. You can define TABLE and VARRAY types in the declarative part of any
PL/SQL block, subprogram, or package. For nested tables, use the syntax
TYPE type_name IS TABLE OF element_type [NOT NULL];
and for varrays, use the following syntax:
TYPE type_name IS {VARRAY | VARYING ARRAY} (size_limit)
OF element_type [NOT NULL];
where type_name is a type specifier used later to declare collections, size_limit
is a positive integer literal, and element_type is any PL/SQL datatype except
BINARY_INTEGER, PLS_INTEGER
BOOLEAN
BLOB, CLOB (restriction applies only to varrays)
LONG, LONG RAW
NATURAL, NATURALN
NCHAR, NCLOB, NVARCHAR2
object types with BLOB or CLOB attributes (restriction applies only to varrays)
object types with TABLE or VARRAY attributes
POSITIVE, POSITIVEN
REF CURSOR
SIGNTYPE
STRING
TABLE
VARRAY