Get history of record states sql server 2008 - sql

Question

Say I had a Bus Garage application that contained a datatable that represented wether buses where either in the garage, out of the garage or in the shop for maintenance. It looks like this:
+-----------------------+-----+-----+
|Date |BusId|State|
+-----------------------+-----+-----+
|2013-09-12 15:02:41,844|1 |IN |
+-----------------------+-----+-----+
|2013-09-12 15:02:41,844|2 |IN |
+-----------------------+-----+-----+
|2013-09-12 15:02:41,844|3 |OUT |
+-----------------------+-----+-----+
|2013-09-12 15:02:41,844|4 |OUT |
+-----------------------+-----+-----+
|2013-09-12 15:02:41,844|5 |OUT |
+-----------------------+-----+-----+
|2013-09-13 15:02:41,844|1 |OUT |
+-----------------------+-----+-----+
|2013-09-14 15:02:41,844|1 |IN |
+-----------------------+-----+-----+
|2013-09-15 15:02:41,844|1 |OUT |
+-----------------------+-----+-----+
|2013-09-15 15:02:41,844|2 |OUT |
+-----------------------+-----+-----+
Now i want to make a nice day-by-day (or hour by hour etc) dataset giving me an overview of how many buses where in the garage an how many that where out of it.
+-------------------+-----+------------+
|Date |State|Count(buses)|
+-------------------+-----+------------+
|2013-09-12 16:00:00|IN |2 |
+-------------------+-----+------------+
|2013-09-12 16:00:00|OUT |3 |
+-------------------+-----+------------+
|2013-09-13 16:00:00|IN |1 |
+-------------------+-----+------------+
|2013-09-13 16:00:00|OUT |4 |
+-------------------+-----+------------+
|2013-09-14 16:00:00|IN |2 |
+-------------------+-----+------------+
|2013-09-14 16:00:00|OUT |3 |
+-------------------+-----+------------+
|2013-09-15 16:00:00|IN |0 |
+-------------------+-----+------------+
|2013-09-15 16:00:00|OUT |5 |
+-------------------+-----+------------+
How (not necessary explained in code) would i go about to do this just using TSQL?
I have one reqirement, and that is that i can not use variable declarations in my statement since i will have this as a View.
I asked a very similar question, but i felt that that one got too verbouse and not as general as this one.

Answer 1

Do you really want multiple records per day/hour just to display the different states? I would make them columns. You can use a CTE and the OVER clause to count per day/hour group:
WITH CTE AS
(
SELECT [Date] = DATEADD(day, DATEDIFF(day, 0, [Date]),0),
[BusId], [State],
[IN] = SUM(CASE WHEN State='IN' THEN 1 END) OVER (PARTITION BY DATEADD(day, DATEDIFF(day, 0, [Date]),0)),
[Out] = SUM(CASE WHEN State='Out' THEN 1 END) OVER (PARTITION BY DATEADD(day, DATEDIFF(day, 0, [Date]),0)),
[DayNum] = ROW_NUMBER() OVER (PARTITION BY DATEADD(day, DATEDIFF(day, 0, [Date]),0)
ORDER BY [Date], [BusID], [State])
FROM dbo.Garage g
)
SELECT [Date], [BusId], [State], [IN], [OUT]
FROM CTE
WHERE [DayNum] = 1
Demo
Result:
DATE BUSID STATE IN OUT
September, 12 2013 00:00:00+0000 1 IN 2 3
September, 13 2013 00:00:00+0000 1 OUT (null) 1
September, 14 2013 00:00:00+0000 1 IN 1 (null)
September, 15 2013 00:00:00+0000 1 OUT (null) 2
This works even in SQL-Server 2005. If you want to group by hour instead of day you have to change DATEADD(day, DATEDIFF(day, 0, [Date]),0) to DATEADD(hour, DATEDIFF(hour, 0, [Date]),0) everywhere.

Answer 2

try this....
DECLARE #businfo AS TABLE([date] datetime,busid int,[state] varchar(5))
INSERT INTO #businfo VALUES('2013-09-12 15:02:41',1,'IN')
INSERT INTO #businfo VALUES('2013-09-12 15:02:41',2,'IN')
INSERT INTO #businfo VALUES('2013-09-12 15:02:41',3,'OUT')
INSERT INTO #businfo VALUES('2013-09-12 15:02:41',4,'OUT')
INSERT INTO #businfo VALUES('2013-09-12 15:02:41',5,'OUT')
INSERT INTO #businfo VALUES('2013-09-13 15:02:41',1,'OUT')
INSERT INTO #businfo VALUES('2013-09-14 15:02:41',1,'IN')
INSERT INTO #businfo VALUES('2013-09-15 15:02:41',1,'OUT')
INSERT INTO #businfo VALUES('2013-09-15 15:02:41',2,'OUT')
select [date],[state],COUNT(busid) as [count(buses)] from #businfo
group by [date],[state]
order by [date]