How to manually initialize a collection of RECORDs in PL/SQL?

There is no "constructor" syntax for RECORDs, so you have to populate them like this:

declare type a is record(a1 number, a2 number); type b is table of a; arr b := b();begin arr.extend(2); arr(1).a1 := 1; arr(1).a2 := 2; arr(2).a1 := 3; arr(2).a2 := 4;end;

This works without objects, but you have to declare a constructor function for type 'a' values.

declare    type a is record(a1 number, a2 number);  type b is table of a;  arr b;  --Constructor for type a  function a_(a1 number, a2 number) return a is    r_a a;  begin    r_a.a1 := a1;    r_a.a2 := a2;    return(r_a);  end;begin  arr := b(a_(1, 2), a_(3, 4), a_(5, 6), a_(7, 8));  for i in arr.first .. arr.last loop    dbms_output.put_line(arr(i).a1||', '||arr(i).a2);  end loop;end;

Since release 18c Qualified Expressions provides an alternative way to define the values of complex data types. Quote:

Starting with Oracle Database Release 18c, any PL/SQL value can be provided by an expression (for example for a record or for an associative array) like a constructor provides an abstract datatype value. In PL/SQL, we use the terms "qualified expression" and "aggregate" rather than the SQL term "type constructor", but the functionality is the same.

Here's an working example:

declare     type a is record (a1 number, a2 number);    type b is table of a index by varchar2 (16);    arr b := b ('key1' => a (1, 2), 'key2' => a (3, 4)); begin     declare key varchar2 (16) := arr.first; begin     <<foreach>> loop        dbms_output.put_line (arr(key).a1||','||arr (key).a2);        key := arr.next (key);        exit foreach when key is null;    end loop; end;end;/PL/SQL procedure successfully completed.1,23,4