Determining SQL MERGE statement result - sql

Question

Is there a way to determine whether a record was matched or not (whether the record was inserted or updated) after calling MERGE?
Ideally I'd like to output it to a parameter.
Edit:
I've got the merge statement outputting what happened in my management studio using the following statement:
Say I had the following merge statement:
MERGE INTO TestTable as target
USING ( select '00D81CB4EA0842EF9E158BB8FEC48A1E' )
AS source (Guid)
ON ( target.Guid = source.Guid )
WHEN MATCHED THEN
UPDATE SET Test_Column = NULL
WHEN NOT MATCHED THEN
INSERT (Guid, Test_Column) VALUES ('00D81CB4EA0842EF9E158BB8FEC48A1E', NULL)
OUTPUT $action;
I'm trying to use a parameter to get the '$action' output.

Answer 1

What you could do is create a temporary table (or a table variable) and send your output there - add some meaningful fields to your OUTPUT clause to make it clear what row was
affected by what action:
DECLARE #OutputTable TABLE (Guid UNIQUEIDENTIFIER, Action VARCHAR(100))
MERGE INTO TestTable as target
USING ( select '00D81CB4EA0842EF9E158BB8FEC48A1E' )
AS source (Guid)
ON ( target.Guid = source.Guid )
WHEN MATCHED THEN
UPDATE SET Test_Column = NULL
WHEN NOT MATCHED THEN
INSERT (Guid, Test_Column) VALUES ('00D81CB4EA0842EF9E158BB8FEC48A1E', NULL)
OUTPUT INSERTED.Guid, $action INTO #OutputTable
SELECT
Guid, Action
FROM
#OutputTable
UPDATE: ah, okay, so you want to call this from .NET ! Well, in that case, just call it using the .ExecuteReader() method on your SqlCommand object - the stuff you're outputting using OUTPUT... will be returned to the .NET caller as a result set - you can loop through that:
using(SqlCommand cmd = new SqlCommand(mergeStmt, connection))
{
connection.Open();
using(SqlDataReader rdr = cmd.ExecuteReader())
{
while(rdr.Read())
{
var outputAction = rdr.GetValue(0);
}
rdr.Close();
}
connection.Close();
}
You should get back the resulting "$action" from that data reader.