SQL MERGE INTO - How to delete then insert matched/existing data? - sql-server

Question

I currently have a stored procedure that compares my target table (Ticket_Report) to my data source table (New_Tickets).
I am using a MERGE INTO statement to compare these two. When it finds a match between the two tables, it updates the current row in the target table with the corresponding info from the source table. If it dosent find a match, it inserts that data from the source table into the target table.
MERGE INTO Ticket_REPORT T1
USING #New_Tickets T2
ON T1.TICKET_NO=T2.TICKET_NO
WHEN MATCHED THEN
UPDATE SET
T1.TICKET_NO = T2.TICKET_NO,
T1.ASSIGNED_GROUP = T2.ASSIGNED_GROUP,
T1.ASSIGNEE = T2.ASSIGNEE,
T1.FNAME = T2.FNAME,
T1.LNAME = T2.LNAME
WHEN NOT MATCHED THEN
INSERT VALUES(
T2.TICKET_NO,
T2.ASSIGNED_GROUP,
T2.ASSIGNEE,
T2.FNAME,
T2.LNAME
);
What I need to do is, when I find a MATCH, instead of just updating the row, I need to delete that row, and re-insert it into the target table. Can anyone show me how to both DELETE and INSERT one after the other whenever I find a MATCH?

Answer 1

Here is an example:
DECLARE #t1 TABLE(id INT IDENTITY, col1 INT)
DECLARE #t2 TABLE(id INT IDENTITY, col1 INT, old_col1 INT)
INSERT INTO #t1(col1) VALUES(5), (10), (15)
INSERT INTO #t2(col1) VALUES(7), (14), (21), (28)
MERGE INTO #t2 t2
USING #t1 t1 ON t1.id = t2.id
WHEN MATCHED THEN DELETE
WHEN NOT MATCHED THEN INSERT VALUES(t1.col1, NULL)
OUTPUT t1.col1, Deleted.col1 INTO #t2(col1, old_col1);
SELECT * FROM #t2
ORDER BY id
Output:
id col1 old_col1
4 28 NULL
5 5 7
6 10 14
7 15 21
First 3 rows have same ids in both, so match part will delete those(7, 14, 21). 28 will remain. And you insert new values and keep old values in OUTPUT clause.

Answer 2

#Giorgi, that doesn't work completely.
If you #t1 has more rows than #t2, there'll be duplicates.
DECLARE #t1 TABLE(id INT IDENTITY, col1 INT)
DECLARE #t2 TABLE(id INT IDENTITY, col1 INT, old_col1 INT)
INSERT INTO #t1(col1) VALUES(5), (10), (15), (20), (25)
INSERT INTO #t2(col1) VALUES(7), (14), (21), (28)
MERGE INTO #t2 t2
USING #t1 t1 ON t1.id = t2.id
WHEN MATCHED THEN DELETE
WHEN NOT MATCHED THEN INSERT VALUES(t1.col1, NULL)
OUTPUT t1.col1, Deleted.col1 INTO #t2(col1, old_col1);
SELECT * FROM #t2
ORDER BY id
id col1 old_col1
5 25 NULL
6 25 NULL
7 5 7
8 10 14
9 15 21
10 20 28

Answer 3

The easiest way is run 2 times
DECLARE #t1 TABLE(id INT IDENTITY, col1 INT)
DECLARE #t2 TABLE(id INT IDENTITY, col1 INT, old_col1 INT)
INSERT INTO #t1(col1) VALUES(5), (10), (15), (20), (25)
INSERT INTO #t2(col1) VALUES(7), (14), (21), (28)
-- FIRST RUN;
MERGE INTO #t2 t2
USING #t1 t1 ON t1.id = t2.id
WHEN MATCHED THEN DELETE
--SECOND RUN;
MERGE INTO #t2 t2
USING #t1 t1 ON t1.id = t2.id
WHEN NOT MATCHED THEN INSERT VALUES(t1.col1, NULL)