SQL Server 2008: подсчет количества ключей в нескольких диапазонах дат

Question

SQL Server 2008 снова. У меня есть первичный ключ pt_id и столбец даты и времени order_dts для каждого идентификатора. Я хочу посчитать количество ключей в каждом году с 1996 по 2008 год и вернуть восемь результатов - подсчет за каждый год. За один год

SELECT COUNT pm.pt_id AS '1996'
FROM dm.medications pm
WHERE (pm.order_dts BETWEEN '1/1/1996' and '12/31/1996')

работает, но как я могу делать все годы без необходимости делать что-то смешное, например, восемь разных запросов?

Спасибо!

Answer 1

SELECT COUNT(*),  Year(pm.order_dts) as Year
FROM dm.medications pm
WHERE Year(pm.order_dts) between 1996 AND 2008
group by Year(pm.order_dts)

Если вы хотите все это в один ряд, вы можете сделать:

SELECT 
    sum(case when Year(pm.order_dts) = 1996 then 1 end) as Count1996,
    sum(case when Year(pm.order_dts) = 1997 then 1 end) as Count1997,
    sum(case when Year(pm.order_dts) = 1998 then 1 end) as Count1998,
    sum(case when Year(pm.order_dts) = 1999 then 1 end) as Count1999,
    sum(case when Year(pm.order_dts) = 2000 then 1 end) as Count2000,
    sum(case when Year(pm.order_dts) = 2001 then 1 end) as Count2001,
    sum(case when Year(pm.order_dts) = 2002 then 1 end) as Count2002,
    sum(case when Year(pm.order_dts) = 2003 then 1 end) as Count2003,
    sum(case when Year(pm.order_dts) = 2004 then 1 end) as Count2004,
    sum(case when Year(pm.order_dts) = 2005 then 1 end) as Count2005,
    sum(case when Year(pm.order_dts) = 2006 then 1 end) as Count2006,
    sum(case when Year(pm.order_dts) = 2007 then 1 end) as Count2007,
    sum(case when Year(pm.order_dts) = 2008 then 1 end) as Count2008
FROM dm.medications pm

Answer 2

select count(pm.pt_id) as count, datepart(yy, pm.order_dts) as year
from dm.medications pm
WHERE (pm.order_dts BETWEEN '1/1/1996' and '12/31/1996')
group by datepart(yy, pm.order_dts)