Question

With Oracle (or DB2, HSQLDB), I can express things like this:

MERGE INTO [target_table]
USING (SELECT 1 FROM dual)
ON [target_table.id = 5]
WHEN MATCHED THEN UPDATE ...
WHEN NOT MATCHED THEN INSERT ...

This just checks if there is already a record with id = 5 in target_table. If there is, then the record is update, if there isn’t then it is inserted. This is roughly the same as MySQL’s more concise

INSERT INTO [target_table] ...
ON DUPLICATE KEY UPDATE ...

How can I do that in SQL Server? According to the documentation, the [table_source] needs to be any of these:

<table_source> ::= 
{
  table_or_view_name [ [ AS ] table_alias ] [ <tablesample_clause> ] 
        [ WITH ( table_hint [ [ , ]...n ] ) ] 
  | rowset_function [ [ AS ] table_alias ] 
        [ ( bulk_column_alias [ ,...n ] ) ] 
  | user_defined_function [ [ AS ] table_alias ]
  | OPENXML <openxml_clause> 
  | derived_table [ AS ] table_alias [ ( column_alias [ ,...n ] ) ] 
  | <joined_table> 
  | <pivoted_table> 
  | <unpivoted_table>
}

http://msdn.microsoft.com/de-de/library/bb510625.aspx

Obviously, SQL Server does not have a DUAL table, but neither is a SELECT statement allowed. What can I put as [table_source] ?

N.B: I found out that I can create a dummy view

CREATE VIEW dummy (one) AS SELECT 1;

and supply that as the [table_source]. But I would like to omit DDL statements just to be able to execute this MERGE statement

Answer 1

See MERGE — look at the example “C. Using MERGE to perform UPDATE and INSERT operations on a target table by using a derived source table” which uses VALUES (aka Table Value Constructor):

MERGE INTO Target
USING (VALUES (1))
       AS Source (Number)
...

Happy coding.