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

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

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;

Answer 6

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; 
        /