mysql - 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 I want to do something like this:

SELECT  `id` ,  `naam` 
FROM  `klanten` 
WHERE IF(`email` > 0,
`email` LIKE  '%@domain.nl%'
,  `email2` LIKE  '%@domain.nl%'
)

How to check if email exist? I want to use email and if this field is empty I want to use email2. How do I accomplish this?

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%'