MS SQL Merge upsert

multiple record writing - steps to achieve the fastest update of an table:

- create temp database table. This is a copy of the destination table to fill for finally.

- fille the temp database table with the bulk copy function of System.data.sqlClient.

- execute the MERGE script.

MERGE example:

MERGE [dbo].[THE_TABLE] as t

USING [dbo].[TEMP_THE_TABLE] as s

ON t.MY_ID=s.MY_ID AND t.MY_SEQUENCE=s.MY_SEQUENCE

WHEN MATCHED THEN 

UPDATE SET

        t.MY_VALUE=s.MY_VALUE,

        t.MY_TIMESTAMP=s.MY_TIMESTAMP

WHEN NOT MATCHED THEN 

INSERT (MY_ID, MY_SEQUENCE, MY_VALUE, MY_TIMESTAMP)

VALUES (s.MY_ID, s.MY_SEQUENCE, s.MY_VALUE, s.MY_TIMESTAMP);

(t=target, s=source)