在using子句中使用"DUAL"的SQL Server MERGE语句

Question

使用Oracle(或DB2,HSQLDB),我可以表达这样的事情:

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

这只是检查是否已经有一个记录id = 5在target_table.如果有,则记录更新,如果没有,则插入.这与MySQL更简洁大致相同

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

我怎么能在SQL Server中这样做？根据文档,[table_source]需要是以下任何一个:

<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

显然,SQL Server没有DUAL表,但也SELECT不允许使用语句.我能放[table_source]什么？

注意:我发现我可以创建一个虚拟视图

CREATE VIEW dummy (one) AS SELECT 1;

并提供作为[table_source].但我想省略DDL语句只是为了能够执行此MERGE语句

Answer 1

见MERGE -看看例如"C.使用合并通过使用衍生源表上的目标表中执行UPDATE和插入操作",它采用VALUES(又名表值构造):

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

快乐的编码.