Obtaining General Information About Linked Servers

You can use both SQL Server Management Studio and the system stored procedures to gather information about linked servers and the referenced data sources. Following are some of the most-often-used system stored procedures:

• sp_linkedservers— This returns a list of linked servers defined on the local server.

• sp_catalogs— This displays a list of catalogs and descriptions for a specified linked server.

• sp_indexes— This shows index information for a specified remote table.

• sp_primarykeys— This returns the primary key columns for the specified table.

• sp_foreignkeys— This lists the foreign keys defined for the remote table.

• sp_tables_ex— This displays table information from the linked server.

• sp_columns_ex— This returns column information for all columns or a specified column for a remote table.

• sp_helplinkedsrvlogin— This displays the linked server login mappings for each linked server.

For example, at query prototyping time, it is useful to see all the ways the linked server objects and columns are being referenced (especially when you’re dealing with other data sources, such as Excel spreadsheets).

First, the exact linked object name is displayed via the sp_tables_ex system stored procedure. In this case, you would see the following for the ACCESS_DATABASE_CUSTOMERS linked server just created:

EXECUTE sp_tables_ex 'ACCESS_DATABASE_CUSTOMERS'
go
TABLE_CAT TABLE_SCHEM TABLE_NAME        TABLE_TYPE   REMARKS
--------- ----------- ------------      ------------ -------
NULL      NULL        MSysAccessObjects ACCESS TABLE
NULL      NULL        MSysACEs          SYSTEM TABLE
NULL      NULL        MSysObjects       SYSTEM TABLE
NULL      NULL        MSysQueries       SYSTEM TABLE
NULL      NULL        MSysRelationships SYSTEM TABLE
NULL      NULL        SWCustomers       TABLE

Then you can see all the table columns of that linked server’s data source by using the sp_columns_ex system stored procedure. The following command provides the column definitions for the SWCustomers Access table for the linked server 'ACCESS_DATABASE_CUSTOMERS':

EXECUTE sp_columns_ex 'ACCESS_DATABASE_CUSTOMERS'
go
TABLE_CAT TABLE_SCH TABLE_NAME        COLUMN_NAME  TYPE_NAME  SIZE
------------------------------------- ------------ ---------- -------
NULL      NULL      MSysAccessObjects Data         VarBinary 3992
NULL      NULL      MSysAccessObjects ID           Long      10
NULL      NULL      SWCustomers       CustomerID   VarChar   255
NULL      NULL      SWCustomers       CompanyName  VarChar   255
NULL      NULL      SWCustomers       ContactName  VarChar   255
NULL      NULL      SWCustomers       ContactTitle VarChar   255
NULL      NULL      SWCustomers       Address      VarChar   255
NULL      NULL      SWCustomers       City         VarChar   255
NULL      NULL      SWCustomers       Region       VarChar   255
NULL      NULL      SWCustomers       PostalCode   Double    15
NULL      NULL      SWCustomers       Country      VarChar   255
NULL      NULL      SWCustomers       Phone        VarChar   255
NULL      NULL      SWCustomers       Fax          VarChar   255