Solutions for INSERT OR UPDATE on SQL Server

Question

Assume a table structure of MyTable(KEY, datafield1, datafield2...).

Often I want to either update an existing record, or insert a new record if it does

Answer 1

Although its pretty late to comment on this I want to add a more complete example using MERGE.

Such Insert+Update statements are usually called "Upsert" statements and can be implemented using MERGE in SQL Server.

A very good example is given here: http://weblogs.sqlteam.com/dang/archive/2009/01/31/UPSERT-Race-Condition-With-MERGE.aspx

The above explains locking and concurrency scenarios as well.

I will be quoting the same for reference:

ALTER PROCEDURE dbo.Merge_Foo2
      @ID int
AS

SET NOCOUNT, XACT_ABORT ON;

MERGE dbo.Foo2 WITH (HOLDLOCK) AS f
USING (SELECT @ID AS ID) AS new_foo
      ON f.ID = new_foo.ID
WHEN MATCHED THEN
    UPDATE
            SET f.UpdateSpid = @@SPID,
            UpdateTime = SYSDATETIME()
WHEN NOT MATCHED THEN
    INSERT
      (
            ID,
            InsertSpid,
            InsertTime
      )
    VALUES
      (
            new_foo.ID,
            @@SPID,
            SYSDATETIME()
      );

RETURN @@ERROR;