Nahradit hodnoty null v SQL pomocí příkazu select v mysql?

Máte mnoho možností, jak nahradit hodnoty NULL v MySQL:

CASE

select case 
    when fieldname is null then '123' 
    else fieldname end as fieldname 
from tablename 

COALESCE

select coalesce(fieldname, '123') as fieldname 
from tablename 

IFNULL

select ifnull(fieldname, '123') as fieldname 
from tablename