I've been able to get this to work fine as long as I'm doing a
straight copy from one TIB_Query to another.

Now, I'm trying to set one of the fields to a constant value if it's
zero. I'm using code like this:

IB_DataPump1.DstRow.ByName('SESSION_ID').AsInteger := 123;

I've tried doing this in AfterFetchRow, BeforeExecuteItems and
AfterExecuteItems, but none of these places worked.


1) If the source (not the destination, but the source) doesn't have
this field, then the destination doesn't either, even though it's in
the SQL so I get an exception.

2) If I provide it in the source, then the value it has in the
source is what I always get.

I tried AfterFetchRow because of something I read in the help file
that implied that this was where one could override mappings. I
even tried changing the row data passed into the event, but I got
a "read only dataset" exception.

The other two where shots in the dark. According to the debugger
the value gets changed, but when the row is viewed in the database,
the original value from the source is in the field, not what I
supplied.

What am I overlooking?