unable to update multiple rows with sql query or trigger(URGENT)

[sanju]

Hi,

I have a table called Photos, where user will have 1 to 10 photos and only
one photo will set to be active at any given point of time.(i.e IsPermitted
='True' and remaining all photos set to false),
user will have an option to make another photo as active.

when this happens newly selected photo should be set to 'True' and rest of
the photos to 'False'

when i am trying to do this using Sql trigger i am getting an error as
follows.

System.Data.SqlClient.SqlException: Subquery returned more than 1 value.
This is not permitted when the subquery follows =, !=, <, <= , >, >= or when
the subquery is used as an expression. The statement has been terminated.

Is there any way to fire the trigger before updating the row with stored
proc.
Any help is much appreciated
Thanks
Sanju