If else on WHERE clause

Question

I\'ve this query:

SELECT  `id` ,  `naam` 
FROM  `klanten` 
WHERE (
`email` LIKE  \'%@domain.nl%\'
OR  `email2` LIKE  \'%@domain.nl%\'
)

But

Answer 1

IF is used to select the field, then the LIKE clause is placed after it:

SELECT  `id` ,  `naam` 
FROM  `klanten` 
WHERE IF(`email` != '', `email`, `email2`) LIKE  '%@domain.nl%'