I'm using WHERE XXX IN (SQL), so (SQL) must select only one Column
In this case I'm select some customer_id from a group, and those customer only belongs to that group only
WHERE `id_customer` IN(
SELECT g.`id_customer` // this must select *only one* column
FROM ps_customer_group AS g
Group By g.`id_customer`
Having COUNT(g.`id_customer`) = 1
AND g.`id_group`=3 // **- Unknown column 'g.id_group' in 'having clause'**
)
the raw data look like this, btw this is not the result
Try this:
WHERE id_customer IN(
select g.id_customer from
ps_customer_group as g
where g.id_group=3 -- That belongs to this group
and g.id_customer in(
SELECT g.id_customer
FROM ps_customer_group AS g
Group By g.id_customer
Having COUNT(g.id_group) = 1 -- is his only group
)
)
Here is a test
In case you want to know if a customer belongs to one group (ID=3) only, you have to change your query:
select g.id_customer
from ps_customer_group AS g
where g.id_customer in (
select id_customer
from ps_customer_group
where id_group=3
)
Group By g.id_customer
Having COUNT(distinct g.id_group) = 1
this will list all customers which belong to group #3 and to no other group.
id_customerand searching for having count = 1. So it will return you more than one values.