Question

I have a situation where I need to insert data from table1 to table2. Before insert check if a certain row already exist in the table2, if it does then just update col2, col4 of the row. If it doesn’t exist then insert a new row.

I am using SQLSERVER 2008 R2. How could I achieve this?

The situation has changed a bit now. I need something like this.

DECLARE @table1 TABLE 
(id int not null, ahccs int not null, info varchar(25), flag varchar(2))
DECLARE @table2 TABLE 
(id int not null, ahccs int not null, info varchar(25), flag varchar(2))

INSERT INTO @table1
VALUES(1, 1223, 'et', 'X')
INSERT INTO @table1
VALUES(2, 321, 'et', 'X')
INSERT INTO @table1
VALUES(3, 134, 'et', 'X' )
INSERT INTO @table1
VALUES(4, 168, 'et', 'X' )
INSERT INTO @table1
VALUES(5, 123, 'et', 'X' )


INSERT INTO @table2
VALUES(1, 1223, 'dt', 'y' )
INSERT INTO @table2
VALUES(2, 456, 'dt', 'y' )
INSERT INTO @table2
VALUES(3, 123, 'dt', 'y' )
INSERT INTO @table2
VALUES(4, 193, 'dt', 'y' )
--SELECT * FROM @table1

SELECT * FROM @table2

MERGE
INTO    @table2 t2
USING   @table1 t1
ON      t2.id = t1.id or t2.ahccs = t1.ahccs
WHEN NOT MATCHED THEN
UPDATE
SET     flag = 'z'
INSERT VALUES (100, t1.ahccs, t1.info, 'l');

The two issues I am having are:
1) Merge doesn’t support multiple steps, I believe.
2) Update is not allowed in WHEN NOT MATCHED case.

Please advise.

Thank You.

Answer 1

MERGE
INTO    table2 t2
USING   table1 t1
ON      t2.id = t1.t2_id
WHEN NOT MATCHED THEN
INSERT  
VALUES  (t1.col1, t1.col2, ...)
WHEN MATCHED THEN
UPDATE
SET     col2 = t1.col2,
        col4 = t1.col4