Question

I have a mySQL table which contains rows based on payments.

Each row contains their e-mail address, so I want to write a query using mySQL and PHP to find out how many people have 2 or more entries in this table.

This is basically to know if they have paid us more than once, by buying two packages, or renewing a subscription.

What would be the best way to do this?

Answer 1

select distinct email, count(*) as rowcount
from datatable
group by email
having rowcount > 1

EDIT: I wrote the above off the top of my head. A quick test on Oracle shows that the syntax is slightly wrong and should be

select distinct email, count(*) as rowcount
from datatable
group by email
having count(*) > 1

But this might just be Oracle not allowing the aliased column in the having clause. I’m not sure what mySQL would allow.