mysql query to select all except something

Question

i\'m trying to select the customers who purchase only vegetables in food table.But i can\'t use except in query.How can i do this?

    create table Order (
            


        

Answer 1

select ro.email
from registerorder ro 
inner join food f on f.namea = ro.namea
group by ro.email
having sum(f.type <> 'vegtables') = 0