SQL Quiz of the Day

Let’s say you have raw data as so:

Id          Counter     Ident
----------- ----------- -----
1           1           A
2           2           A
3           1           A
4           3           B
5           3           B
6           2           A
7           1           A
8           4           C
9           2           C
10          1           B
11          1           B
12          4           B

And you want to group by the Ident field, but
only contiguous blocks.  So you want to display
the following:

Counter     Ident
----------- -----
4           A
6           B
3           A
6           C
6           B

Naturally one can’t use GROUP BY, because this would
aggregate multiple A’s and B’s.

Answers on a postcard!

====

CREATE TABLE [dbo].[Test](
        [Id] [int] IDENTITY(1,1) NOT NULL,
        [Counter] [int] NOT NULL,
        [Ident] [varchar](3)
         COLLATE Latin1_General_CI_AS NOT NULL,
 CONSTRAINT [PK_Test] PRIMARY KEY CLUSTERED
(
        [Id] ASC
)WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]