How many assets does each third party company supply? List the count and the company id.
SELECT count(*) ,  T1.company_id FROM Third_Party_Companies AS T1 JOIN Assets AS T2 ON T1.company_id  =  T2.supplier_company_id GROUP BY T1.company_id
count of assets supplied by each third party company refers to COUNT(*); list the count and the company id refers to SELECT count(*) , company_id; using JOIN to link Third_Party_Companies and Assets tables based on company_id and supplier_company_id respectively;