Need help in converting INSERT\UPDATE to MERGE - sql-server-2008

Question

Is this a good candidate for a MERGE command?
Must the source data also be another table or can it be variables that are passed?
If it must be a table, is inserting the passed variables into a temp table sane?
Could you help me with the syntax?
CREATE PROCEDURE [dbo].[usp_ConvertToMerge]
#GL_DT date
,#SRC_SYS_ID varchar(60)
,#MLR_SRC_SYS_CD char(3)
,#TRSRY_FEED_DT date
,#Data varchar(20)
AS
BEGIN
IF NOT EXISTS (SELECT
#GL_DT
FROM
MLR_REBATE_IBOR_INFO_2
WHERE
[GL_DT] = #GL_DT
AND [SRC_SYS_ID] = #SRC_SYS_ID
AND [MLR_SRC_SYS_CD] = #MLR_SRC_SYS_CD
AND [TRSRY_FEED_DT] = #TRSRY_FEED_DT)
BEGIN
INSERT INTO [dbo].[MLR_REBATE_IBOR_INFO_2]
([GL_DT],
[SRC_SYS_ID],
[MLR_SRC_SYS_CD],
[TRSRY_FEED_DT],
[Data])
SELECT
#GL_DT
,#SRC_SYS_ID
,#MLR_SRC_SYS_CD
,#TRSRY_FEED_DT
,#Data
END
ELSE
BEGIN
UPDATE [dbo].[MLR_REBATE_IBOR_INFO_2]
SET [Data] = #Data
WHERE [GL_DT] = #GL_DT
AND [SRC_SYS_ID] = #SRC_SYS_ID
AND [MLR_SRC_SYS_CD] = #MLR_SRC_SYS_CD
AND [TRSRY_FEED_DT] = #TRSRY_FEED_DT
END
END
GO

Answer 1

I think I did it:
CREATE PROCEDURE MyMergeTest
#GL_DT date
,#SRC_SYS_ID char(20)
,#MLR_SRC_SYS_CD char(3)
,#TRSRY_FEED_DT date
,#Data varchar(20)
AS
BEGIN
MERGE MLR_REBATE_IBOR_INFO_2 AS target
USING
(
SELECT
#GL_DT
,#SRC_SYS_ID
,#MLR_SRC_SYS_CD
,#TRSRY_FEED_DT
,#Data
) AS source
(
GL_DT
,SRC_SYS_ID
,MLR_SRC_SYS_CD
,TRSRY_FEED_DT
,Data
)
ON (
target.GL_DT = source.GL_DT AND
target.SRC_SYS_ID = source.SRC_SYS_ID AND
target.MLR_SRC_SYS_CD = source.MLR_SRC_SYS_CD AND
target.TRSRY_FEED_DT = source.TRSRY_FEED_DT
)
WHEN MATCHED THEN
UPDATE SET Data = source.Data
WHEN NOT MATCHED THEN
INSERT
(
[GL_DT],
[SRC_SYS_ID],
[MLR_SRC_SYS_CD],
[TRSRY_FEED_DT],
[Data]
)
VALUES
(
[GL_DT], --<<it looks like these can eiether be the variable eg, #GL_DT, or prefixed by 'source.'
[SRC_SYS_ID],
[MLR_SRC_SYS_CD],
[TRSRY_FEED_DT],
[Data]
);
END