Question

I have a mssql stored procedure question for you experts:

I have two tables [table1] which retrieves new entries all the time. I then have another table [table2] which I need to copy the content of [table1] into.

I need to check if some of the the rows already exists in [table2], if it do, just update the Update-timestamp of [table2], otherwise insert it into [table2].

The tables can be rather big, about 100k entries, so which is the fastest way to do this?

It should be noticed that this is a simplified idea, since there is some more datahandling happening when copying new content from [Table1] -> [Table2].

So to sum up:
If a row exist both [Table1] and [Table2] update the timestamp of the row in [Table2] otherwise just insert a new record with the content into [Table1].

Answer 1

This works across all versions of SQL Server. MERGE does the same in SQL Server 2008.

UPDATE
    table2
SET
    timestampcolumn = whatever
WHERE
    EXISTS (SELECT * 
       FROM table1
       WHERE
           table1.key = table2.key)


INSERT table2 (col1, col2, col3...)
SELECT col1, col2, col3...
FROM table1
WHERE
    NOT EXISTS (SELECT * 
       FROM table2
       WHERE
           table2.key = table1.key)