How To Use The NVL() Function In Statement

I have the following query.

sql

Original

- sql Code

SELECT class, COUNT (class)
FROM nv_table
WHERE l_id IN (
SELECT l_id
FROM n_table
WHERE id IN (1234)
GROUP BY class
ORDER BY class

SELECT class, COUNT (class) 
FROM nv_table 
WHERE l_id IN (          SELECT l_id            FROM n_table           WHERE id IN (1234)   
GROUP BY class   
ORDER BY class

It returns two columns: class and the total number of values in that class.

In some cases, there might not be any values under a certain class, so the query won't return anything.

In such a case I want the query to return 0. So what I want to see is:

class:A, COUNT(class):0

I'm trying to use the NVL function here, but either it doesn't work in this context, or it's not the correct syntax the way I'm writing it.

sql

Original

- sql Code

SELECT class, NVL(COUNT (class), 0)
FROM nv_table
WHERE l_id IN (
SELECT l_id
FROM n_table
WHERE id IN (1234)

[Code]....