An extended stored procedure is a function within a DLL 
(written in a programming language like C, C++ using Open 
Data Services (ODS) API) that can be called from T-SQL, 
just the way we call normal stored procedures using the 
EXEC statement.


Yes, you can instantiate a COM (written in languages like 
VB, VC++) object from T-SQL by using sp_OACreate stored 
procedure.  For an example of creating a COM object in VB 
and calling it from T-SQL

An extended stored procedure is simply a procedure that is 
implemented in a dynamic link library (DLL) — a library 
that is called by an application at runtime. Extended 
stored procedures can be used in much the same way as 
database stored procedures, except that extended stored 
procedures normally perform tasks related to the 
interaction of SQL Server with its operating environment. 
Tasks that are either too complicated or just not possible 
using Transact-SQL can often be performed with extended 
stored procedures.
Extended stored procedures are written using the Open Data 
Services (ODS) API. ODS is written and supported by 
Microsoft and is available on the Workstation version of 
SQL Server and as a separate product (and in the Back-
Office Development Kit). The ODS development package 
includes both a static-link library (Opends60.lib) and C 
header files that let you create fully functional database 
services. ODS applications are dynamically linked with 
Opends60.dll.

SOme are the type of Extend Stored Procedure..
XP_Cmdshell, xp_logevent, xp_deletemail, xp_sendmail

An extended stored procedure is simply a procedure that is 
implemented in a dynamic link library (DLL) — a library 
that is called by an application at runtime. Extended 
stored procedures can be used in much the same way as 
database stored procedures, except that extended stored 
procedures normally perform tasks related to the 
interaction of SQL Server with its operating environment. 
Tasks that are either too complicated or just not possible 
using Transact-SQL can often be performed with extended 
stored procedures.
Extended stored procedures are written using the Open Data 
Services (ODS) API. ODS is written and supported by 
Microsoft and is available on the Workstation version of 
SQL Server and as a separate product (and in the Back-
Office Development Kit). The ODS development package 
includes both a static-link library (Opends60.lib) and C 
header files that let you create fully functional database 
services. ODS applications are dynamically linked with 
Opends60.dll.

SOme are the type of Extend Stored Procedure..
XP_Cmdshell, xp_logevent, xp_deletemail, xp_sendmail