SQL Server 2005 Implementation Of MySQL REPLACE INTO?

MySQL has this incredibly useful yet proprietary REPLACE INTO SQL Command.

Can this easily be emulated in SQL Server 2005?

Starting a new Transaction, doing a Select() and then either UPDATE or INSERT and COMMIT is always a little bit of a pain, especially when doing it in the application and therefore always keeping 2 versions of the statement.

I wonder if there is an easy and universal way to implement such a function into SQL Server 2005?

This is something that annoys me about MSSQL (rant on my blog). I wish MSSQL supported upsert.

@Dillie-O's code is a good way in older SQL versions (+1 vote), but it still is basically two IO operations (the exists and then the update or insert)

There's a slightly better way on this post, basically:

--try an update
update tablename 
set field1 = 'new value',
    field2 = 'different value',
    ...
where idfield = 7

--insert if failed
if @@rowcount = 0 and @@error = 0
    insert into tablename 
           ( idfield, field1, field2, ... )
    values ( 7, 'value one', 'another value', ... )

This reduces it to one IO operations if it's an update, or two if an insert.

MS Sql2008 introduces merge from the SQL:2003 standard:

merge tablename as target
using (values ('new value', 'different value'))
    as source (field1, field2)
    on target.idfield = 7
when matched then
    update
    set field1 = source.field1,
        field2 = source.field2,
        ...
when not matched then
    insert ( idfield, field1, field2, ... )
    values ( 7,  source.field1, source.field2, ... )

Now it's really just one IO operation, but awful code :-(