I am trying to update a field in a table with data from another table, based on a common key. If it were in straight SQL, it would be something like:

Update EHSIT
set e.IDMSObjID = s.IDMSObjID
from EHSIT e, EHSIDMS s
where e.SITENUM = s.SITE_CODE

However, the two tables are not in the same database, so I'm trying to use SSIS to do the update. Oh, and the sitenum/site_code are varchar in one and nvarchar in the other, so I'll have to do a data conversion so they'll match.

How do I do it?
I have a data flow object, with the source as EHSIDMS and the destination as EHSIT. I have a data conversion to convert the unicode to non-unicode. But how do I update based on the match? I've tried with the destination, using a SQL Command as the Data Access mode, but it doesn't appear to have the source table. If I just map the field to be updated, how does it limit it based on fields matching?

I'm about to export my source table to Excel or something, and then try inputting from there, although it seems that all that would get me would be to remove the data conversion step.

Shouldn't there be an update data task or something? Is it one of those Data Flow transformation tasks, and I'm just not figuring out which it is?