A relatively common piece of logic in a database application is to check for a row's existence and then either update or insert depending on its existence.
SQL:2003 added a MERGE statement to perform this operation. It looks like this:
MERGE INTO table_name USING table_name ON (condition)
WHEN MATCHED THEN UPDATE SET column1 = value1 [, column2 = value2 ...]
WHEN NOT MATCHED THEN INSERT column1 [, column2 ...] VALUES (value1 [, value2 ...])
At the moment, the only workaround for this would be to write a stored procedure to do the same operation, or to implement the logic client-side.