Object Model (Updates) vs. Domain Model (Selects)

I might have the term's all wrong here, I am just trying to work out the best way to implement SQL updates on my sites.
With the SQL select statements, I create a DTO, or sometimes a complex DTO (classes referanced inside class) and create an object that basicly has one field per column. The SELECT has many joins and so is a good SELECT DTO, but not a good update DTO. The reason is that the DTO does not always contain all of the columns for each table that is joined on, but for the columns selected.
When I need to do an update, this does not matchup very well unless I do an UPDATE with the same joins in as the SELECT.
The performance of the updates is not so important as I beleive the website user excepts they are in edit mode and does not expect the same perforance as when reading.
I am thinking of creating  DTO's that represents each SQL table, so I can do a SELECT / UPDATE / INSERT for each table, as I can select the whole table and then pass ...