06533. 00000 - "Subscript beyond count" - oracle

Question

I have this plsql block that populates a table with information of two other tables and I have to use a variable array:
DECLARE nombre_grupo VARCHAR2(15);
direccion_tipo direccion;
persona_tipo persona;
personas_array personas := personas();
CURSOR departamento IS
SELECT * FROM departamentos;
CURSOR empleado IS
SELECT * FROM empleados, departamentos
WHERE empleados.dept_no = departamentos.dept_no;
i INTEGER;
BEGIN
FOR departamento IN (SELECT * FROM departamentos) LOOP
nombre_grupo := departamento.dnombre;
i := 1;
personas_array := personas();
FOR empleado IN (SELECT * FROM empleados WHERE dept_no = departamento.dept_no) LOOP
direccion_tipo := DIRECCION(departamento.loc, 'NULL', empleado.dir);
personas_array(i) := PERSONA(empleado.emp_no, empleado.apellido,
direccion_tipo, empleado.fecha_alt);
i := i + 1;
END LOOP;
INSERT INTO grupos VALUES (nombre_grupo, personas_array);
END LOOP;
END;
Here's the type personas:
CREATE OR REPLACE TYPE personas AS VARRAY(5) OF PERSONA
So when I execute that block and it reaches the personas_array(i) bit, it exits the execution with "subscript beyond count" error, no matter what value of i. What am I missing?
I've already deleted and created the type personas again, I've also tried creating the type inside the procedure, but it can't insert into the table

Answer 1

A few tips for a SQL beginner:
Don't learn 30 years old Oracle join syntax. Use modern ANSI join syntax, i.e.
SELECT *
FROM empleados
JOIN departamentos ON empleados.dept_no = departamentos.dept_no;
Your cursors are redundant. Either use
DECLARE
CURSOR cur_departamento IS
SELECT *
FROM departamentos;
BEGIN
FOR departamento IN cur_departamento LOOP
...
END LOOP;
END;
or
DECLARE
BEGIN
FOR departamento IN (SELECT * FROM departamentos) LOOP
...
END LOOP;
END;
You can also use this:
DECLARE
CURSOR cur_empleados(d IN EMPLEADOS.DEPT_NO%TYPE) IS
SELECT *
FROM EMPLEADOS
WHERE dept_no = d;
/*
-- Do not use this!
CURSOR cur_empleados(dept_no IN EMPLEADOS.DEPT_NO%TYPE) IS
SELECT *
FROM EMPLEADOS
WHERE EMPLEADOS.dept_no = dept_no; -> will return all rows
*/
BEGIN
FOR departamento IN (SELECT * FROM departamentos) LOOP
FOR empleado IN cur_empleados(departamento.dept_no) LOOP
...
END LOOP;
END LOOP;
END;
According to my feelings, VARRAYs are often part of student material but hardly used in real life.
Using string 'NULL' is most likely not want you want. Use literal NULL, i.e.
DIRECCION(departamento.loc, NULL, empleado.dir)
Type VARRAY(5) OF PERSONA defines a varray with maximum size of 5 elements. When you initialize it with personas_array := personas(); then the actual size is 0. You need to extend the varray.
You code may look like this:
DECLARE
nombre_grupo VARCHAR2(15);
direccion_tipo direccion;
persona_tipo persona;
personas_array personas;
i INTEGER;
BEGIN
FOR departamento IN (SELECT * FROM departamentos) LOOP
nombre_grupo := departamento.dnombre;
i := 1;
personas_array := personas();
FOR empleado IN (SELECT * FROM empleados WHERE dept_no = departamento.dept_no AND ROWNUM <= 5) LOOP
direccion_tipo := DIRECCION(departamento.loc, NULL, empleado.dir);
personas_array.extend();
personas_array(i) := PERSONA(empleado.emp_no, empleado.apellido, direccion_tipo, empleado.fecha_alt);
i := i + 1;
END LOOP;
INSERT INTO grupos VALUES (nombre_grupo, personas_array);
END LOOP;
END;
Just a note, such procedure would have rather low performance. The professional way of doing it would be a Nested Table and then insert the data with a single command:
CREATE OR REPLACE TYPE personas_NT AS TABLE OF PERSONA;
INSERT INTO grupos VALUES (nombre_grupo, personas_array)
SELECT dnombre,
CAST(MULTISET(
SELECT
emp_no,
apellido,
DIRECCION(dept.loc, NULL, dir),
fecha_alt
FROM EMPLEADOS
WHERE dept_no = dept.dept_no
) AS personas_NT) AS personas_array
FROM DEPARTAMENTOS dept;
But maybe, that would be a chapter in the "advanced" SQL course.