How to Loop department names - sql

Question

Oracle SQL Developer
I want to Loop department id and department names starting from dep_id = 10 and till 50th department. Departments are increasing by 10, so, there are 5 departments from 10 to 50.
Here's my code
DECLARE
dep_name VARCHAR(15);
dep_id NUMBER;
BEGIN
SELECT department_name, department_id INTO dep_name, dep_id FROM Departments
WHERE DEPARTMENT_ID = 10;
LOOP
IF dep_id < 51 THEN
DBMS_OUTPUT.PUT_LINE('Deparment id is ' || dep_id);
dep_id := dep_id + 10;
DBMS_OUTPUT.PUT_LINE('Deparment name is ' || dep_name);
ELSE
EXIT WHEN dep_id > 51;
END IF;
END LOOP;
END;
And here is the output,
Deparment id is 10
Deparment name is Administration
Deparment id is 20
Deparment name is Administration
Deparment id is 30
Deparment name is Administration
Deparment id is 40
Deparment name is Administration
Deparment id is 50
Deparment name is Administration
But as you can see the Administration row is repeating itself.
The output should be like this
Deparment id is 10
Deparment name is Administration
Deparment id is 20
Deparment name is Marketing
Deparment id is 30
Deparment name is Purchasing
Deparment id is 40
Deparment name is Human Resources
Deparment id is 50
Deparment name is Shipping
What am I supposed to do about this?
Thanks!

Answer 1

How about a simple cursor FOR loop?
SQL> set serveroutput on;
SQL> begin
2 for cur_d in (select department_id, department_name
3 from departments
4 where department_id between 10 and 50
5 )
6 loop
7 dbms_output.put_line('Department ID is ' || cur_d.department_id);
8 dbms_output.put_line('Department name is ' || cur_d.department_name);
9 end loop;
10 end;
11 /
Department ID is 10
Department name is Administration
Department ID is 20
Department name is Marketing
Department ID is 30
Department name is Purchasing
Department ID is 40
Department name is Human Resources
Department ID is 50
Department name is Shipping
PL/SQL procedure successfully completed.
SQL>

Answer 2

If the loop is mandatory
DECLARE
dep_name VARCHAR(15);
dep_id NUMBER;
BEGIN
dep_id:=10;
LOOP
IF dep_id < 51 THEN
DBMS_OUTPUT.PUT_LINE('Deparment id is ' || dep_id);
SELECT department_name INTO dep_name FROM Departments
WHERE DEPARTMENT_ID = dep_id;
DBMS_OUTPUT.PUT_LINE('Deparment name is ' || dep_name);
dep_id := dep_id + 10;
ELSE
EXIT WHEN dep_id > 51;
END IF;
END LOOP;
END;

Answer 3

You could avoid the loop .. using a simply (correct) query
SELECT department_name, department_id
FROM Departments
WHERE DEPARTMENT_ID between 10 AND 50;
(your code is wrong, you are only selecting the id = 10 not the values from 10 to 50 )

Answer 4

It seems the major requirement is to print department id and name. That does indeed require a plsql loop; and a cursor to hold the data after the select. Further, you should NOT relay on a specific interval between department id. Instead let the query and the cursor holding result set control the entire process.
declare
cursor c_department_list is
select department_name, department_id
from departments
where department_id <= 50 ;
l_dept_name departments.department_name%type;
l_dept_id departments.department_id%type;
begin
open c_department_list;
loop
fetch c_department_list
into l_dept_name, l_dept_id;
exit when c_department_list%notfound.
dbms_output.put_line(' Deparment id is ' || l_dep_id ||
'. Deparment name is ' || l_dep_name);
end loop;
close c_department_list;
end;
References: Cursors, Loop
The above uses a technique referred to as explicit cursor. There is another preferred (perhaps easier) technique referred to as implicit cursor. I will leave that to your research.