MySQL: Stored function not accepting null from view field

[Roger Palacios]

I have the following query that call stored function:

select count(*)
from vw_estatus_empleados vw
where nivel_color_id('Cumplimiento', vw.estatus_actual) = -1;

The `nivel_color_id` function returns `-1` when second parameter is null.

Actually, **the `vw.estatus_actual` field have `null` in all rows**.

When I run the query above the results is:

+----------+
| count(*) |
+----------+
| 0 |
+----------+

By other hand, when I run the same query with `null` instead of `vw.estatus_actual`:

select count(*)
from vw_estatus_empleados vw
where nivel_color_id('Cumplimiento', null) = -1;

The result is:

+----------+
| count(*) |
+----------+
| 19 |
+----------+


Here is the function header:

CREATE DEFINER=...
FUNCTION `nivel_color_id`(`escala` VARCHAR(16), `valor` FLOAT)
RETURNS int(11)

Why this could happed?


A view row sample:

SELECT * FROM vw_estatus_empleados
WHERE estatus_actual IS NULL;

+-------------+--------------+----------------+
| id_empleado | id_proveedor | estatus_actual |
+-------------+--------------+----------------+
| 11 | 16 | NULL |
| 8 | 11 | NULL |
| 4 | 2 | NULL |
| 19 | 23 | NULL |
| 13 | 18 | NULL |
+-------------+--------------+----------------+