Question

I have to query two different servers from a dynamically built query.

It basically gets data from one server, treats it, and inserts it into another server.

The only problem is I have to be sure it works for both situations:
If both the source and destination databases are on the same server, and if they’re not.

I understand the concept of using Linked Servers in SQL Server, but I cannot think of a way to consider both alternatives, same server and different servers.

A little help?

Answer 1

Two linked servers are not necessary… just one per server. Example

PhysicalServerA
   SQLServerA
      DatabaseA
      DatabaseB
   LinkedSQLServerB  // A linked server to SQL Server B

PhysicalServerB
   SQLServerB
      DatabaseC
      DatabaseD
   LinkedSQLServerA  // A linked Server to SQL Server A

Now Server A can have queries to itself like:

SELECT * FROM SQLServerA.DatabaseA.dbo.TableName

And queries to LinkedSQLServerB like

SELECT * FROM SQLServerB.DatabaseC.dbo.TableName

Now Server B can have queries to itself like:

SELECT * FROM SQLServerB.DatabaseC.dbo.TableName

And queries to LinkedSQLServerA like

SELECT * FROM SQLServerA.DatabaseA.dbo.TableName