Chapter 20. Using ADO for Searching

Microsoft's ADO technology lets you conduct database searches and retrieve the results through a flexible interface called resultsets. ADO also lets you update information in a database directly or with stored procedures. Because Microsoft created an ADO database provider for ADSI (the ADSI OLE DB provider), you can also use ADO's database query technology to query Active Directory. However, the ADSI OLE DB provider is currently read-only, so many of the useful ADO methods for updating data aren't available yet. You can use ADO only for searching and retrieving objects. Despite the read-only limitation, using ADO is still a boon. It is significantly faster to search Active Directory using ADO than it is to use ADSI to bind to each object recursively down a branch. Even using IADsContainer::Filter is slow in comparison. So if you need to search Active Directory rapidly for attributes matching criteria, ADO is exactly what you should use. The ADO object model consists of nine objects (Command, Connection, Error, Field, Parameter, Property, Record, Recordset, and Streams) and four collection objects (Errors, Fields, Parameters, and Properties). However, some of these objects aren't useful if you're using the ADSI OLE DB provider, as they are more often used for accessing full-fledged database services. For example, the Parameter object lets you pass parameters to stored procedures, but this object is of little use because the ADSI provider doesn't support stored procedures.

The objects that are appropriate to ADSI in a read-only environment are the Command, Connection, Error, Field, Property, and Recordset objects. We use them to show you how to perform complex searches. For a full description of the ADO object model and the available functions, check out the following on the MSDN Library (http://msdn.microsoft.com/library/): Data Access Microsoft Data Access Components (MDAC) SDK Documentation Microsoft ActiveX Data Objects (ADO).

If you wish to make use of the tools in this chapter in a VB project rather than a VBScript script, you need to include the Microsoft ActiveX Data Objects 2.x library from the Reference item on the Project menu of the Visual Basic Environment.

One point to note: ADO is written to work with all types of databases, so there are a numerous ways of doing exactly the same thing. We will attempt to cover examples of each different way as they crop up so that you will be able to choose the method that suits you best or that you are familiar with.