T-SQL-Elemente zählen durch Hinzufügen und Entfernen

Question

In SQL Server 2008 habe ich Table1 und ich möchte die Ausgabe wie in der erwarteten Ausgabe angezeigt bekommen. Jedes Mal, wenn Aktion 'Count' auftritt, werden alle relevanten Elemente hinzugefügt/entfernt und die Summe angezeigt. Angenommen, alle Elemente beginnen mit 0.

Vielen Dank.

CREATE TABLE Table1([Time] [smalldatetime] NULL,[Action] [nvarchar](10) NULL,[Item] [nchar](50) NULL) 
insert into Table1 values('2009-08-22 20:34:02','Count','Apple') 
insert into Table1 values('2009-08-22 20:34:03','Count','Banana') 
insert into Table1 values('2009-08-22 20:34:04','Count','Mango') 
insert into Table1 values('2009-08-22 20:34:05','Count','Black Berry') 
insert into Table1 values('2009-08-22 20:34:06','Count','Orange') 
insert into Table1 values('2009-08-22 20:34:07','Add','Apple') 
insert into Table1 values('2009-08-22 20:34:08','Add','Banana') 
insert into Table1 values('2009-08-22 20:34:09','Add','Mango') 
insert into Table1 values('2009-08-22 20:34:10','Remove','Banana') 
insert into Table1 values('2009-08-22 20:34:11','Add','Banana') 
insert into Table1 values('2009-08-22 20:34:12','Add','Mango') 
insert into Table1 values('2009-08-22 20:34:13','Add','Mango') 
insert into Table1 values('2009-08-22 20:34:14','Add','Mango') 
insert into Table1 values('2009-08-22 20:34:15','Remove','Mango') 
insert into Table1 values('2009-08-22 20:34:17','Count','Apple') 
insert into Table1 values('2009-08-22 20:34:18','Add','Banana') 
insert into Table1 values('2009-08-22 20:34:19','Add','Banana') 
insert into Table1 values('2009-08-22 20:34:20','Remove','Banana') 
insert into Table1 values('2009-08-22 20:34:21','Add','Apple') 
insert into Table1 values('2009-08-22 20:34:22','Add','Mango') 
insert into Table1 values('2009-08-22 20:34:23','Add','Apple') 
insert into Table1 values('2009-08-22 20:34:24','Add','Mango') 
insert into Table1 values('2009-08-22 20:34:25','Remove','Apple') 
insert into Table1 values('2009-08-22 20:34:26','Count','Mango') 
insert into Table1 values('2009-08-22 20:34:27','Add','Apple') 
insert into Table1 values('2009-08-22 20:34:28','Add','Banana') 
insert into Table1 values('2009-08-22 20:34:29','Remove','Apple') 
insert into Table1 values('2009-08-22 20:34:30','Remove','Banana') 
insert into Table1 values('2009-08-22 20:34:31','Add','Banana') 
insert into Table1 values('2009-08-22 20:34:32','Add','Mango') 
insert into Table1 values('2009-08-22 20:34:33','Count','Banana') 
insert into Table1 values('2009-08-22 20:34:34','Add','Banana') 
insert into Table1 values('2009-08-22 20:34:35','Add','Apple') 
insert into Table1 values('2009-08-22 20:34:36','Remove','Mango') 
insert into Table1 values('2009-08-22 20:34:37','Add','Apple') 
insert into Table1 values('2009-08-22 20:34:38','Add','Mango') 
insert into Table1 values('2009-08-22 20:34:39','Count','Apple') 
insert into Table1 values('2009-08-22 20:34:40','Remove','Apple') 
insert into Table1 values('2009-08-22 20:34:41','Remove','Banana') 
insert into Table1 values('2009-08-22 20:34:42','Add','Banana') 
insert into Table1 values('2009-08-22 20:34:43','Add','Mango') 
insert into Table1 values('2009-08-22 20:34:44','Count','Banana') 
insert into Table1 values('2009-08-22 20:34:45','Remove','Banana') 
insert into Table1 values('2009-08-22 20:34:46','Remove','Apple') 
insert into Table1 values('2009-08-22 20:34:47','Remove','Mango') 
insert into Table1 values('2009-08-22 20:34:48','Add','Apple') 
insert into Table1 values('2009-08-22 20:34:49','Add','Mango') 
insert into Table1 values('2009-08-22 20:34:50','Count','Mango') 

Answer 1

Dies kann mit einer linken äußeren Selbst erreicht werden kommen, wie unten gezeigt jedoch die erzeugten Ergebnisse unterscheiden von dem, was Sie wahrscheinlich gezeigt haben, weil Sie einige Rechenfehler gemacht. Wie auch immer, versuche einen ähnlichen Ansatz.

select a.time,a.item, 
SUM(case 
when b.action='Add' then 1 
when b.action='Remove' then -1 
else 0 end) 
from table1 as a 
left join table1 as b 
on a.item=b.item 
and b.time<a.time 
where a.action='Count' 
group by a.time,a.item,a.action 
order by 1