Which shipping agent shipped the most documents? List the shipping agent name and the number of documents.
create table documents (id varchar, PRIMARY KEY (id)); create table ref_shipping_agents (id varchar, PRIMARY KEY (id))
select ref_shipping_agents.shipping_agent_name, count(documents.document_id) from ref_shipping_agents join documents on documents.shipping_agent_code = ref_shipping_agents.shipping_agent_code group by ref_shipping_agents.shipping_agent_code order by count(documents.document_id) desc limit 1