What is the name of the shipping agent that shipped the largest number of documents?
select t1.shipping_agent_name from ref_shipping_agents as t1 join documents as t2 on t2.shipping_agent_code = t1.shipping_agent_code group by t1.shipping_agent_code order by count ( t2.document_id ) desc limit 1
What is the name of the shipping agent that shipped the smallest number of documents?
select t1.shipping_agent_name from ref_shipping_agents as t1 join documents as t2 on t2.shipping_agent_code = t1.shipping_agent_code group by t1.shipping_agent_code order by count ( t2.document_id ) limit 1
What are the receipt dates of all of the documents Airline shipped?
select t2.receipt_date from ref_shipping_agents as t1 join documents as t2 on t2.shipping_agent_code = t1.shipping_agent_code where t1.shipping_agent_name = "Airline"