Oracle PL/SQL - How to create a simple array variable? - oracle

Question

I'd like to create an in-memory array variable that can be used in my PL/SQL code. I can't find any collections in Oracle PL/SQL that uses pure memory, they all seem to be associated with tables. I'm looking to do something like this in my PL/SQL (C# syntax):
string[] arrayvalues = new string[3] {"Matt", "Joanne", "Robert"};
Edit:
Oracle: 9i

Answer 1

You can use VARRAY for a fixed-size array:
declare
type array_t is varray(3) of varchar2(10);
array array_t := array_t('Matt', 'Joanne', 'Robert');
begin
for i in 1..array.count loop
dbms_output.put_line(array(i));
end loop;
end;
Or TABLE for an unbounded array:
...
type array_t is table of varchar2(10);
...
The word "table" here has nothing to do with database tables, confusingly. Both methods create in-memory arrays.
With either of these you need to both initialise and extend the collection before adding elements:
declare
type array_t is varray(3) of varchar2(10);
array array_t := array_t(); -- Initialise it
begin
for i in 1..3 loop
array.extend(); -- Extend it
array(i) := 'x';
end loop;
end;
The first index is 1 not 0.

Answer 2

You could just declare a DBMS_SQL.VARCHAR2_TABLE to hold an in-memory variable length array indexed by a BINARY_INTEGER:
DECLARE
name_array dbms_sql.varchar2_table;
BEGIN
name_array(1) := 'Tim';
name_array(2) := 'Daisy';
name_array(3) := 'Mike';
name_array(4) := 'Marsha';
--
FOR i IN name_array.FIRST .. name_array.LAST
LOOP
-- Do something
END LOOP;
END;
You could use an associative array (used to be called PL/SQL tables) as they are an in-memory array.
DECLARE
TYPE employee_arraytype IS TABLE OF employee%ROWTYPE
INDEX BY PLS_INTEGER;
employee_array employee_arraytype;
BEGIN
SELECT *
BULK COLLECT INTO employee_array
FROM employee
WHERE department = 10;
--
FOR i IN employee_array.FIRST .. employee_array.LAST
LOOP
-- Do something
END LOOP;
END;
The associative array can hold any make up of record types.
Hope it helps,
Ollie.

Answer 3

You can also use an oracle defined collection
DECLARE
arrayvalues sys.odcivarchar2list;
BEGIN
arrayvalues := sys.odcivarchar2list('Matt','Joanne','Robert');
FOR x IN ( SELECT m.column_value m_value
FROM table(arrayvalues) m )
LOOP
dbms_output.put_line (x.m_value||' is a good pal');
END LOOP;
END;
I would use in-memory array. But with the .COUNT improvement suggested by uziberia:
DECLARE
TYPE t_people IS TABLE OF varchar2(10) INDEX BY PLS_INTEGER;
arrayvalues t_people;
BEGIN
SELECT *
BULK COLLECT INTO arrayvalues
FROM (select 'Matt' m_value from dual union all
select 'Joanne' from dual union all
select 'Robert' from dual
)
;
--
FOR i IN 1 .. arrayvalues.COUNT
LOOP
dbms_output.put_line(arrayvalues(i)||' is my friend');
END LOOP;
END;
Another solution would be to use a Hashmap like #Jchomel did here.
NB:
With Oracle 12c you can even query arrays directly now!

Answer 4

Another solution is to use an Oracle Collection as a Hashmap:
declare
-- create a type for your "Array" - it can be of any kind, record might be useful
type hash_map is table of varchar2(1000) index by varchar2(30);
my_hmap hash_map ;
-- i will be your iterator: it must be of the index's type
i varchar2(30);
begin
my_hmap('a') := 'apple';
my_hmap('b') := 'box';
my_hmap('c') := 'crow';
-- then how you use it:
dbms_output.put_line (my_hmap('c')) ;
-- or to loop on every element - it's a "collection"
i := my_hmap.FIRST;
while (i is not null) loop
dbms_output.put_line(my_hmap(i));
i := my_hmap.NEXT(i);
end loop;
end;

Answer 5

Sample programs as follows and provided on link also https://oracle-concepts-learning.blogspot.com/
plsql table or associated array.
DECLARE
TYPE salary IS TABLE OF NUMBER INDEX BY VARCHAR2(20);
salary_list salary;
name VARCHAR2(20);
BEGIN
-- adding elements to the table
salary_list('Rajnish') := 62000; salary_list('Minakshi') := 75000;
salary_list('Martin') := 100000; salary_list('James') := 78000;
-- printing the table name := salary_list.FIRST; WHILE name IS NOT null
LOOP
dbms_output.put_line ('Salary of ' || name || ' is ' ||
TO_CHAR(salary_list(name)));
name := salary_list.NEXT(name);
END LOOP;
END;
/

Answer 6

Using varray is about the quickest way to duplicate the C# code that I have found without using a table.
Declare your public array type to be use in script
type t_array is varray(10) of varchar2(60);
This is the function you need to call - simply finds the values in the string passed in using a comma delimiter
function ConvertToArray(p_list IN VARCHAR2)
RETURN t_array
AS
myEmailArray t_array := t_array(); --init empty array
l_string varchar2(1000) := p_list || ','; - (list coming into function adding final comma)
l_comma_idx integer;
l_index integer := 1;
l_arr_idx integer := 1;
l_email varchar2(60);
BEGIN
LOOP
l_comma_idx := INSTR(l_string, ',', l_index);
EXIT WHEN l_comma_idx = 0;
l_email:= SUBSTR(l_string, l_index, l_comma_idx - l_index);
dbms_output.put_line(l_arr_idx || ' - ' || l_email);
myEmailArray.extend;
myEmailArray(l_arr_idx) := l_email;
l_index := l_comma_idx + 1;
l_arr_idx := l_arr_idx + 1;
END LOOP;
for i in 1..myEmailArray.count loop
dbms_output.put_line(myEmailArray(i));
end loop;
dbms_output.put_line('return count ' || myEmailArray.count);
RETURN myEmailArray;
--exception
--when others then
--do something
end ConvertToArray;
Finally Declare a local variable, call the function and loop through what is returned
l_array t_array;
l_Array := ConvertToArray('email1#gmail.com,email2#gmail.com,email3#gmail.com');
for idx in 1 .. l_array.count
loop
l_EmailTo := Trim(replace(l_arrayXX(idx),'"',''));
if nvl(l_EmailTo,'#') = '#' then
dbms_output.put_line('Empty: l_EmailTo:' || to_char(idx) || l_EmailTo);
else
dbms_output.put_line
( 'Email ' || to_char(idx) ||
' of array contains: ' ||
l_EmailTo
);
end if;
end loop;