Merge update source table and delete from target table problem

Question

Hello Friends, 
I am a newbie in SQL Server world and I am in a situation where I need to delete the bunch of records from the TARGET table using the values from the SOURCE table. 
The TARGET table has close to 400 Million records, so I need to delete the records in small batches of about ~10,000 rows.
I figured out a way to delete in batches by refering the following 2 posts
http://sqlperformance.com/2013/03/io-subsystem/chunk-deletes
http://dba.stackexchange.com/questions/1750/methods-of-speeding-up-a-huge-delete-from-table-with-no-clauses
I think my best option to delete and update in 1 pass would be through using Merge statement, so for that I constructed following SQL.
MERGE dbo.table1 AS TARGET
USING 
SELECT File_name FROM dbo.table2
WHERE  FILE_DESC = 'EDI'
AND [Processed_date] < DATEADD (WEEK, -10, Getdate ()) AS SOURCE
ON (TARGET.File_name = SOURCE.File_name)
WHEN MATCHED THEN DELETE (FROM THE TARGET)
WHEN MATCHED 
    THEN UPDATE SET SOURCE.PROCESS_delete_date = GETDATE()
But, when executed, it throws following error and I am struggling to figure out what is wrong with the above syntax. 
Msg 156, Level 15, State 1, Line 3
Incorrect syntax near the keyword 'SELECT'.
Msg 156, Level 15, State 1, Line 5
Incorrect syntax near the keyword 'AS'.
Can any expert please help a newbie as I learn the new way.
Thanks a lot.

Answer 1

Visakh, we can have more than 1 matched clause in merge as per the Microsoft sql statement, but we need to add a condition along with the match. thanks for your prompt response on this query. your query is logically fine but when executed, it throws
following error. Msg 156, Level 15, State 1, Line 2 Incorrect syntax near the keyword 'DELETE'. Msg 102, Level 15, State 1, Line 8 Incorrect syntax near ')'. remember, my server machine is 2005 version & my work machine is 2012. dont know why your query
is not working.
MERGE is available only from 2008 onwards
Yes you're correct but again not more than two  MATCHED clauses even if you specify condition
see MSDN documentation below
WHEN MATCHED THEN <merge_matched>
Specifies that all rows of target_table that match the rows returned by <table_source> ON <merge_search_condition>, and satisfy any additional search condition, are either updated or deleted according to the <merge_matched> clause.
The MERGE statement can have at most two WHEN MATCHED clauses. If two clauses are specified, then the first clause must be accompanied by an AND <search_condition> clause
from
http://msdn.microsoft.com/en-us/library/bb510625.aspx
Also I guess Composable DML which used is also not present in 2005
So in your case you can try this instead
DECLARE @DELETED_FILES table
File_Name varchar(100)
DELETE t
OUTPUT DELETED.File_Name INTO @DELETED_FILES
FROM dbo.table1 t
INNER JOIN dbo.table2 s
ON t.File_name = s.File_name
WHERE s.FILE_DESC = 'EDI'
AND s.[Processed_date] < DATEADD (WEEK, -10, Getdate ())
UPDATE r
SET r.Process_Delete_Date = GETDATE()
FROM dbo.table2 r
INNER JOIN @DELETED_FILES AS p
ON p.File_Name = r.File_Name
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Visakh
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