Обратиться к таблице по её ID

use tempdb;
go
 
create table dbo.Table1 (id int identity, v int, table_id int default (1), check (table_id = 1), primary key (id, table_id));
create table dbo.Table2 (id int identity, v int, table_id int default (2), check (table_id = 2), primary key (id, table_id));
go
 
create view dbo.vAggregatedTable
as
select table_id, id, v from dbo.Table1
union all
select table_id, id, v from dbo.Table2
go
 
insert into dbo.Table1 (v) values (1);
insert into dbo.Table2 (v) values (2);
 
select * from dbo.vAggregatedTable;
select * from dbo.Table1;
select * from dbo.Table2;
go
 
declare @t table (table_id int, id int, new_v int);
insert into @t
values
 (1, 1, 10), (2, 1, 20);
 
update vagt
 set
  v = t.new_v
from
 @t t join
 dbo.vAggregatedTable vagt on vagt.table_id = t.table_id and vagt.id = t.id;
 
select * from dbo.vAggregatedTable;
select * from dbo.Table1;
select * from dbo.Table2;
go
 
drop view dbo.vAggregatedTable;
drop table dbo.Table1, dbo.Table2;
go