Show me a list of all shipping agent codes
select shipping_agent_code from ref_shipping_agents
add a column showing the total number of documents shipped per code
select shipping_agent_code, count ( * ) from documents group by shipping_agent_code
Add another column showing the shipping agent name
select t1.shipping_agent_code, t1.shipping_agent_name, count ( * ) from ref_shipping_agents as t1 join documents as t2 on t2.shipping_agent_code = t1.shipping_agent_code group by t2.shipping_agent_code