Question

Assume there are two tables: Remote_table and My_table.

Remote_table has 6 columns:

PROJECT   JOB_TYPE   MONTH  YEAR**       HOURS     IS_DELETED
134393     70         1       2013      30     0
134393     70         2       2013      50     0
134393     70         3       2013      80     0
134393     70         10      2012      10     0
134393     70         11      2012      0      0
134393     70         12      2012      15     0

My_table is a copy of remote_table.

I tried to copy only the new records from the remote_table by this query:

SELECT    *
FROM [remote_DB].[LudanProjectManager].[dbo].Remote_table            
EXCEPT           
SELECT    *
FROM My_table

It works OK but I get a duplicate primary key exception when changes have been made on the remote_table on the hours column.

Can anyone think of a way to copy only the new records from remote_table and if changes has been made on old records, to identify them and update the my_table to correspond?

Answer 1

Since you are using SQL Server 2008, you can use MERGE :

MERGE INTO My_table AS TGT
USING Remote_table AS SRC
  ON TGT.PROJECT = SRC.PROJECT, -- This is the matching condition. 
     TGT.YEAR    = SRC.YEAR,
   ---
WHEN NOT MATCHED THEN
  INSERT(PROJECT, JOB_TYPE, MONTH, YEAR, HOURS, IS_DELETED)
  VALUES(SRC.PROJECT, SRC.JOB_TYPE, SRC.MONTH, SRC.YEAR, SRC.HOURS,
         SRC.IS_DELETED);

Note that:

• The matched and unmatched rows are determined based on the coditions specified in the ON clause, may be you need to restrict the matching rows using extra conditions , TGT.Year = SRC.TGT, .. or just matched on the PROJECT field only using ON TGT.PROJECT = SRC.PROJECT.
• You have to end the MEREGE statement with a semicolon. It is mandatory.
• In the INSERT statement there was no INTO TableName because the name of the target table is already defined in the MERGE clause.