Preamble
In Oracle PL/SQL Varray (an array with variable size) is an array whose number of elements can vary from zero (empty) to the declared maximum size.
To access a Varray element, use the variable_name(index) syntax:
- The lower boundary of the index is 1; the upper boundary is the current number of elements.
- The upper limit changes when the elements are added or removed, but it cannot exceed the maximum size.
When you store and extract a varray from the database, its indexes and the order of the elements remain stable.
Syntax to define and then declare a Varrays type variable in Oracle PL/SQL
TYPE type_varray IS {VARRAY | VARYING ARRAY} (size_limit) OF element_type [NOT NULL];
v_arr type_varray;
Parameters and arguments of the array
- type_varray – name of type Varray
- element_type – any PL/SQL data type, except for REF CURSOR
- size_limit is a positive integer literal representing the maximum number of elements in the array.
- v_arr – the name of a variable of the Varray type
Note:
- When defining a Varray type, you must specify its maximum size.
An example of how to use Varray in Oracle PL/SQL
DECLARE
TYPE Foursome IS VARRAY(4) OF VARCHAR2(15); -- Varray type
-- is a varray variable initialized by the constructor:
team Foursome := Foursome('John', 'Mary', 'Alberto', 'Juanita');
PROCEDURE print_team (heading VARCHAR2) IS
BEGIN
DBMS_OUTPUT.PUT_LINE(heading);
FOR i IN 1..4 LOOP
DBMS_OUTPUT.PUT_LINE(i) || '.' || team(i));
END LOOP;
DBMS_OUTPUT.PUT_LINE('---');
END;
BEGIN
print_team('2001 Team:');
team(3) := 'Pierre'; -- Change the values of the two elements
team(4) := 'Yvonne';
print_team('2005 Team:');
-- Call the constructor to assign new values to the Varray variable:
team := Foursome('Arun', 'Amitha', 'Allan', 'Mae');
print_team('2009 Team:');
END;
As a result, we get:
2001 Team:
1.John
2.Mary
3.Alberto
4.Juanita
---
2005 Team:
1.John
2.Mary
3.Pierre
4.Yvonne
---
2009 Team:
1.Arun
2.Amitha
3.Allan
4.Mae
---
In this example we defined Foursome as a local Varray type, declared a team variable of this type (initialized by the constructor) and defined the print_team procedure which printed Varray. The example calls the procedure three times:
- after initializing the variable,
- after changing values of two elements separately,
- and after using the constructor to change the value of all elements.
Using Varray
Varray should be used when:
- You know the maximum number of elements.
- You access the elements in sequence.
- Since you must store or retrieve all elements simultaneously, Varray may not be practical for a large number of elements.
PL/SQL tutorial: VARRAYs in Oracle Database
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