Xin chào, bạn có thể sử dụng một cái gì đó như thế này
select connections.connection_id, contacts.contact_id companies.companyid
from connections
left join companies on connections.company_id = companies.company_id
left join contacts on contacts.contact_id = connections.contact_id
where company_name LIKE ('%qwer%')
and contact_name LIKE('%abc%')