how to validate date null in mysql?

I'm working with MariaDB. when I try to show some result don't show me nothing.

select 
    if(fecha is null,'hello','bye') dat
from 
    table

I'm trying to show me some result, but I don't know how?

You can use something like this

CREATE TABLE t1 (fecha  VARCHAR(2))

SELECT IF( COUNT(*) = 0 , 'Empty',`fecha`) FROM t1

| IF( COUNT(*) = 0 , 'EMpty',`fecha`) |
| :---------------------------------- |
| EMpty                               |

db<>fiddle here