Question

I have two tables: hosts and events. Every event has a hostid. I would like to find out how many hosts have at least three events – I have come up with the following:

SELECT COUNT(*) FROM hosts,events
WHERE hosts.id=events.host_id COUNT(hosts.id)>=3

But it gives me the error “Invalid use of group function”.

How can I solve that?

Answer 1

try this:

SELECT   hosts.id,count(*)
FROM     hosts 
JOIN     events 
ON       hosts.id=events.host_id
GROUP BY hosts.id
HAVING   count(*)>=3