Trigger to update existing data or insert if data does not exist (multi-row suppport)

Question

I have two tables, both tables contain similar columns of "username", "Date" and "Time". One table (table 2) is essentially a summation of the 'time' column per date where table1 can have multiple "time's" per date.

I have no control over any statements used to insert data into table1 so I thought the best way to do this would be to use a trigger on table1 which inserts into or updates table2 depending on whether a row is already there for the date(s) inserted. To do this, something similar to the following would be fine:

IF NOT EXISTS(SELECT * FROM table2 WHERE date = @date/*date from inserted*/)
    --insert into table 2 here
ELSE
    --update table 2 here

However, the problem is that I also need multi-row support on the trigger which would result in the previous IF failing. One idea would be to loop each row of the insert but from what I've read this will have a big impact on performance which I want to avoid (this is a last resort if there is no better way).

So, is there a way to do what I need without using a some kind of loop?

An example insert which I would be using:

INSERT INTO table2 (username, date, time)
SELECT i.username, i.date, SUM(w.time) FROM inserted AS i
JOIN (SELECT username, date, time FROM table1/*table with trigger*/) AS w 
ON w.date = i.date AND w.username = i.username 
GROUP BY i.username, i.date

Thanks in advance for any advice!

Note: I'm new to SQL so sorry if I'm missing anything/making obvious mistakes!

EDIT (Solution):

The working solution (thanks to the answer by @Ronak Vyas) is as follows:

MERGE table2 AS m
USING (SELECT i.username, i.date, SUM(w.time) FROM inserted AS i
JOIN (SELECT username, date, time FROM table1/*table with trigger*/) AS w 
ON w.date = i.date AND w.username = i.username 
GROUP BY i.username, i.date) AS s
ON m.date = s.date AND m.username = s.username
WHEN MATCHED THEN UPDATE SET m.duration = s.duration
WHEN NOT MATCHED THEN
INSERT (username, date, time)
VALUES (s.username, s.date, s.time)

Thanks a lot!

Answer 1

Try to Use Merge Statement.

Visit http://blog.sqlauthority.com/2008/08/28/sql-server-2008-introduction-to-merge-statement-one-statement-for-insert-update-delete/

Hope, this will help.