Grouping Based On Time Series

In SQL Server 2005, I want to do a set query on the following data that results in 3 groups:









Id
EventName
EventTime

1
First
41:40.2

2
First
41:41.6

3
First
41:43.1

4
First
41:44.4

5
Second
41:46.4

6
Second
41:48.3

7
Second
41:49.7

8
First
41:51.2

9
First
41:53.3

10
First
41:55.0

So, I want to have a query that returns one aggregate row for each of rows 1-4, 5-7 and 8-10 based on the EventName. Every time EventName 'changes' in the order that I sort it, I want to start a new grouping:








Group
EventName
Count

1
First
4

2
Second
3

3
First
3

With this query, I could also get the Min() and Max() EventTime for each group, etc.

However, this is proving difficult to do in set SQL. Obviously, if I group on EventName, then rows 1-4 *and* 8-10 will be rolled into my 'First' group. However, there is no other partitioning information that I can factor in that splits this data into *only* 3 groups, based on the order of the Event Time.

I have tried the various ranking functions, but the problem persists through any combination of function, PARTITION BY and ORDER BY that I can find.

Any insights would be appreciated!