Prova detta:
SELECT orders.orderID,
GROUP_CONCAT(contacts.firstName, " ", contacts.lastName) AS attachedContacts
FROM orders
JOIN contacts ON orders.contactID=contacts.contactID
GROUP BY orders.orderID DESC
HAVING attachedContacts LIKE '%Eric%'
Prova detta:
SELECT orders.orderID,
GROUP_CONCAT(contacts.firstName, " ", contacts.lastName) AS attachedContacts
FROM orders
JOIN contacts ON orders.contactID=contacts.contactID
GROUP BY orders.orderID DESC
HAVING attachedContacts LIKE '%Eric%'