Harvey,

maybe you are referring to *Datasource* OnDataChange event and not Dataset.
Beware that some time ago I hit some difficulties due to the fact that
TDataSource.OnDataChange event fires for every column, and apart that this
was not exactly what I wanted, I experienced some weird behaviour in my
program's logic. IMHO best to use AfterScroll.

If all you want is a lookup of values from another table, this is not a
master/detail relationship and to have it working you have to bind the
lookup dataset to the main one via KeyLinks. KeyDescLinks and KeySource
properties. Once they are correctly set all is automatic.

Regards
Salvatore