Can I use IF inside FROM in Mysql?

Question

It would be possible to do IF within the FROM?
I looked but couldn’t find anything about it.

Follow an example of what I want to do:

SELECT usuario.* FROM (
  SELECT
  IF( 
    (SELECT COUNT(*) FROM pessoa) > 0, 
    SELECT  FROM pessoa,
    SELECT * FROM clliente, 
  ) AS usuario
)

NOTE: As the bank architecture was developed in the worst way, I’m having to do some crazy things in SQL.

Answer 1

A solution can be to create a view

create or replace view v_pessoa_cliente
as
select cpf , nome from pessoa
union
select cpf,nome from cliente

In the application do

select *
from v_pessoa_cliente
where nome = 'Daniel Dutra'

Answer 2

Simplifying like that would no longer solve your case?

SELECT IF(COUNT(p.*) > 0, p.*, c.*) as usuarios_maior_volume
FROM pessoas p, clientes c;

And to catch global:

SELECT * FROM pessoas, clientes;

And to bring it all:

SELECT * FROM pessoas
union all
SELECT * FROM clientes;