compter le nombre d'entrées dans un mois

Question

J'ai une table de commande, et il a une colonne datetime appelée order_date. Je veux compter le nombre de commandes pour chaque mois en 2009. Comment ferais-je cela?

Answer 1

select month(order_date) as orderMonth, count(*) as orderCount 
from order 
where year(order_date) = 2009 
group by month(order_date) 
order by month(order_date) 

Pour référence, voir month et year commandes Transact-SQL.

Answer 2

SELECT MONTH(order_date) AS ordermonth, 
    COUNT(*) AS ordercount 
FROM order 
WHERE YEAR(order_date) = 2009 
GROUP BY ordermonth; 

Answer 3

Que diriez-vous d'utiliser une astuce DATETIME?

select 
    DATEADD(MONTH, DATEDIFF(MONTH, 0, order_date), 0) AS orderMonth, count(*) as orderCount 
from 
    [order] 
where 
    order_date >= '2009-01-01' 
group by 
    DATEADD(MONTH, DATEDIFF(MONTH, 0, order_date), 0) 
order by 
    orderMonth