Updating

Thanks for all who assisted with my previous question on grouping.

I would like to do an update of a table with the results of a query on
another.

For example:

table vehcost

id		serial
po		varchar(12)
veh_no		varchar(8)
cost		real
comments	varchar(30)


table vehinfo

id            serial
veh_no		varchar(12)
m_cost        real
...


I would like to take the sum of vehcost.veh_no and update that info to
field vehinfo.m_cost.

So far, I have worked with the following without success:

update vehinfo set m_cost = (select sum(vehcost.cost) from vehcost group by
veh_no) where vehinfo.veh_no = vehcost.veh_no ; 

Any ideas.

Thanks in advance for any assistance.

Regards - Bob Kruger