SELECT count(*) ,  T1.maintenance_contract_id FROM Maintenance_Contracts AS T1 JOIN Assets AS T2 ON T1.maintenance_contract_id  =  T2.maintenance_contract_id GROUP BY T1.maintenance_contract_id
How many assets does each maintenance contract contain? List the number and the contract id.
SELECT count ( * ) , T1.maintenance_contract_id FROM Maintenance_Contracts AS T1 JOIN Assets AS T2 ON T1.maintenance_contract_id = T2.maintenance_contract_id GROUP BY T1.maintenance_contract_id
select count ( * ) , t1 . maintenance_contract_id from maintenance_contracts as t1 join assets as t2 on t1 . maintenance_contract_id = t2 . maintenance_contract_id group by t1 . maintenance_contract_id
How many assets does each maintenance contract contain ? List the number and the contract id .