simple tsql counter table

gistfile1.sql

-- CREATE TABLE [dbo].[Counter](
--     [id] [bigint] IDENTITY(1,1) NOT NULL,
--     [date] [date] NOT NULL,
--     [key] [varchar](100) NOT NULL,
--     [count] [int] NOT NULL,
--     CONSTRAINT [PK_Counter] PRIMARY KEY CLUSTERED  ([id] ASC)
-- );

BEGIN TRAN
MERGE dbo.[Counter] as t
USING (SELECT 'mykey', '2015-03-30') AS s ([key], [date])
ON t.[key] = s.[key] AND t.[date] = s.[date]
WHEN MATCHED THEN
    UPDATE SET t.[Count] = t.[Count] + 1 -- increment
WHEN NOT MATCHED THEN
    INSERT ([key], [date], [Count])
    VALUES ('mykey', '2015-03-30', 1);
COMMIT TRAN

SELECT * FROM dbo.[Counter]