Question:
I need a query that retrieves info from an Oracle table and a query that retrieves info from a SQL Server table. The info has to be joined together according to Record ID numbers. I have very limited access to the Oracle database but full control of the SQL Server database.

How do I join two different queries from two different databases?

Answer:
To query to different data sources, you can make the Oracle server a linked server to the SQL Server server. A linked server can be any OLE DB data source and SQL Server currently supports the OLE DB data provider for Oracle. You can add a linked server by calling sp_AddLinkedServer and query information about linked servers with sp_LinkedServers.

An easier way to add a linked server is to use Enterprise Manager. Add the server through the Linked Servers icon in the Security node. Once a server is linked, you can query it using a distributed query (you have to specify the full name).

Here’s an example of a distributed query (from the SQL Server Books Online) that queries the Employees table in SQL Server and the Orders table from Oracle:

SELECT emp.EmloyeeID, ord.OrderID, ord.DiscountFROM SQLServer1.Northwind.dbo.Employees AS emp,OracleSvr.Catalog1.SchemaX.Orders AS ordWHERE ord.EmployeeID = emp.EmployeeIDAND ord.Discount > 0