Need help with the Merge statement

Question

I want to update a table called Sorels_ext from a table called Sorels. The link between them is the fkey_id of Sorels_ext equals the identity_column of the Sorels table. This is my first attempt at a Merge statement and I'm trying to learn the syntax.

MERGE Sorels_ext AS SORe
USING (select SOR.identity_column, CASE
        WHEN left(SOR.FPARTNO, 2) = 'BL' THEN 'Blue'
        WHEN left(SOR.FPARTNO, 2) = 'RD' THEN 'Red'
        ELSE 'White'
      END from Sorels AS SOR)
ON  (SORe.fkey_id = SOR.identity_column)

WHEN MATCHED THEN
  UPDATE SET SORe.fkey_id = SOR.identity_column, SORe.Color = select SOR.identity_column, CASE
        WHEN left(SOR.FPARTNO, 2) = 'BL' THEN 'Blue'
        WHEN left(SOR.FPARTNO, 2) = 'RD' THEN 'Red'
        ELSE 'White'
      END
WHEN NOT MATCHED THEN
  INSERT (SORe.fkey_id, SORe.Color) VALUES (SOR.identity_column, SORe.Color = select SOR.identity_column, CASE
        WHEN left(SOR.FPARTNO, 2) = 'BL' THEN 'Blue'
        WHEN left(SOR.FPARTNO, 2) = 'RD' THEN 'Red'
        ELSE 'White'
      END);

When I run this, I get the following error:

Error 10/22/2009 1:38:51 PM 0:00:00.000 SQL Server Database Error: Incorrect syntax near the keyword 'ON'. 46 0

*** ADDED INFO ******

After the first fix suggested, the code is as follows:

    MERGE Sorels_ext AS SORe
USING (select SOR.identity_column, CASE
        WHEN left(SOR.FPARTNO, 2) = 'BL' THEN 'Blue'
        WHEN left(SOR.FPARTNO, 2) = 'RD' THEN 'Red'
        ELSE 'White'
      END from Sorels) AS SOR
ON  (SORe.fkey_id = SOR.identity_column)

WHEN MATCHED THEN
  UPDATE SET SORe.fkey_id = SOR.identity_column, SORe.Color = CASE
        WHEN left(SOR.FPARTNO, 2) = 'BL' THEN 'Blue'
        WHEN left(SOR.FPARTNO, 2) = 'RD' THEN 'Red'
        ELSE 'White'
      END
WHEN NOT MATCHED THEN
  INSERT (SORe.fkey_id, SORe.Color) VALUES (SOR.identity_column, CASE
        WHEN left(SOR.FPARTNO, 2) = 'BL' THEN 'Blue'
        WHEN left(SOR.FPARTNO, 2) = 'RD' THEN 'Red'
        ELSE 'White'
      END);

Now I get the following error:

Error 10/22/2009 2:03:29 PM 0:00:00.000 SQL Server Database Error: The insert column list used in the MERGE statement cannot contain multi-part identifiers. Use single part identifiers instead. 55 0

******* ADDED MORE INFO ****** After adjustments from suggestions, I have the following:

    MERGE Sorels_ext AS SORe
USING (select SOR1.identity_column, CASE
        WHEN left(SOR1.FPARTNO, 2) = 'BL' THEN 'Blue'
        WHEN left(SOR1.FPARTNO, 2) = 'RD' THEN 'Red'
        ELSE 'White'
      END as colors from Sorels as SOR1 ) as SOR 
ON  (SORe.fkey_id = SOR.identity_column)

WHEN MATCHED THEN
  UPDATE SET SORe.fkey_id = SOR.identity_column, SORe.Color = CASE
        WHEN left(SOR.FPARTNO, 2) = 'BL' THEN 'Blue'
        WHEN left(SOR.FPARTNO, 2) = 'RD' THEN 'Red'
        ELSE 'White'
      END
WHEN NOT MATCHED THEN
  INSERT (fkey_id, Color) VALUES (SOR.identity_column, CASE
        WHEN left(SOR.FPARTNO, 2) = 'BL' THEN 'Blue'
        WHEN left(SOR.FPARTNO, 2) = 'RD' THEN 'Red'
        ELSE 'White'
      END);

I get the error:

Error 10/22/2009 2:46:51 PM 0:00:00.000 SQL Server Database Error: Invalid column name 'FPARTNO'. 56 0

What am I doing wrong?

**** I GOT IT!!! *****

MERGE Sorels_ext AS SORe
USING (select SOR.identity_column, CASE
        WHEN left(SOR.FPARTNO, 2) = 'BL' THEN 'Blue'
        WHEN left(SOR.FPARTNO, 2) = 'RD' THEN 'Red'
        ELSE 'White'
      END as colors from Sorels as SOR) SOR1  
ON  (SORe.fkey_id = SOR1.identity_column)

WHEN MATCHED THEN
  UPDATE SET SORe.fkey_id = SOR1.identity_column, SORe.Color = SOR1.colors
WHEN NOT MATCHED THEN
  INSERT (fkey_id, Color) VALUES (SOR1.identity_column, SOR1.colors);

Answer 1

INSERT (SORe.fkey_id, SORe.Color) 

should read:

INSERT (fkey_id, Color) 

Columns in the insert list can only refer to the target table. The parser doesn't expect to see a table alias there, and doesn't know how to resolve it.

If it sees "column1", it knows it belongs to the target table. It sees "table1.column1", it doesn't know what "table1" means, since "table1" as a token is out of scope.

Answer 2

I believe you have to alias your your source data like so:

USING (select SOR.identity_column, 
   CASE  WHEN left(SOR.FPARTNO, 2) = 'BL' 
   THEN 'Blue'        
   WHEN left(SOR.FPARTNO, 2) = 'RD' 
   THEN 'Red'        
   ELSE 'White'      
   END from Sorels AS SOR) **AS SOR** ON  (SORe.fkey_id = SOR.identity_column)