ActiveX Data Objects

ADO is Microsofts universal data-access technology. This means that it can be used to obtain data from almost any source.
There are three versions of ADO in common use: 2.1, 2.5 and 2.6. Version 2.5 comes as standard with Windows 2000 or higher.
When using ADO you must have a reference to (Microsoft ActiveX Data Objects 2.5 Library) or the corresponding version in your Tools > References for that current Project
ADO doesn't actually access the data source directly but through a OLE DB.
Most OLE DB providers are specific to a single type of data source
Dynaset - a query based recordeset
You have the option to The default cachesize is 1 for ADO, which makes a trip for every row.
ADO is much simpler to use than OLE DB and can be classified as a high-level database interface. Also, ADO can be used with more programming languages than OLE DB. ADO provides an Automation interface. This enables ADO to be used from scripting languages, such as VBScript and JavaScript.
This replaces DAO for Office 2007+

Objects

Out of the seven objects four of them (Connection, Command, Recordset and Parameter) can be created and manipulated independently of the others.
These objects can then be associated with others at run-time via the properties ActiveConnection and ActiveCommand.
Connection -
Command - Allows you to issue commands to the database
RecordSet - An array of rows
Parameter - A collection
Stream - Not commonly used in Excel or Word applications

ADO will create objects even if you do not create them explicitly. For example a Recordset object always requires a connection object.
When a recordset is opened by passing a connection string, (and not a connection object), ADO creates an invisible connection object for you.
You should always explicitly create your connection object and re-use it where possible to avoid creating multiple connections to the same data source each time code is executed

Fields Collection

Name	Type	Description
Attributes	Property	Sets or returns the attributes of the field
Name	Property	Sets or returns the name of the field
Numeric Scale	Property	adjusts the scale of the field (only applicable on field types asNumeric & adSmallInt)
Precision	Property	adjusts the precision of the field (only applicable on field types asNumeric & adSmallInt)
AppendChunk	Method	Appends long binary
OriginalValue	Property	Returns the original value in the field
UnderlyingValue	Property	Returns the current value of the field
ActualSize	Property	Returns the actual length of a fields value
DefinedSize	Property	Returns the defined size of the field
Status	Property	Returns the status of the field
Type	Property	Sets ot returns the type of the field
Value	Property	Sets or returns the value of the field
GetChunk	Method	Returns all or part of the contents of a large text or binary data field

Properties Collection

This contains any extended provider specific propertues for the Connection object

Errors Collection

Allows you to retrieve information when an error occurs
This contains not only errors but messages and warnings.
This collection should really be analysed if a collection cannot be made to the relevant data source
This object contains details about data Access errors that have been generated suring a single operation.

Extension Library

References
Microsoft ADO Ext. 2.5 for DDL and Security
Microsoft ADO Ext. 2.6 for DDL and Security
SS - include from References dialog