Question

I have two tables a main table and a work in progress table. Any inserts/updates are inserted into the WIP table while the record is being manipulated, this allows for validation checks and the like. I want to create a view that combines the two tables showing the WIP table data whenever it exists and the main table data when there is no WIP data.

I have figured out a way to do this but it seems that it’s not the most elegant solution. I would like to know if there are other ideas or better solutions?

Example illustrating the situation:

select mt.id, wt.id wip_id, isnull(wt.name,mt.name) name, 
       isnull(wt.address, mt.address) address
from main_table mt full outer join
       wip_table wt on mt.id = wt.orig_id;

So that will pull results from the WIP table when they exist, if they dont it will pull results from the main table. This was a simple example but the tables could have many rows.

Answer 1

if you want data either from one table or the other:

select top 1 *
from
(
select 1 as prio, wt.name, wt.address, .... from wip_table wt where ...
union
select 2 as prio, mt.name, mt.address, .... from main_table mt where ...
order by prio
) x

otherwise, like you have done (checking individual columns), but maybe using a left outer join rather than a full one:

select 
  mt.id
  , wt.id wip_id
  , isnull(wt.name,mt.name) name
  , isnull(wt.address, mt.address) address
from main_table mt left outer join wip_table wt 
  on mt.id = wt.orig_id;