ActiveX Data Objects: Difference between revisions

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{{Short description|Component Object Model APIs for accessing data sources}}

{{Use mdy dates|date=January 2019}}

{{Use American English|date=January 2019}}

{{no footnotes|date=February 2013}}

In [[computing]], [[Microsoft]]'s '''ActiveX Data Objects''' ('''ADO''') comprises a set of [[Component Object Model]] (COM) [[object (computing)|object]]s for accessing data sources. A part of [[Microsoft Data Access Components|MDAC]] (Microsoft Data Access Components), it provides a [[middleware]] layer between [[programming language]]s and [[OLE DB]] (a means of accessing data stores, whether [[database]]s or not, in a uniform manner). ADO allows a [[software developer|developer]] to write programs that access data without knowing how the database is implemented; developers must be aware of the database for connection only. No knowledge of [[SQL]] is required to access a database when using ADO, although one can use ADO to execute SQL commands directly (with the disadvantage of introducing a dependency upon the type of database used).

Microsoft introduced ADO in October 1996, positioning the software as a successor to Microsoft's earlier object layers for accessing data sources, including [[Remote Data Objects|RDO]] (Remote Data Objects) and [[Jet Data Access Objects|DAO]] (Data Access Objects).

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: A stream, mainly used in a RecordSet object, is a means of reading and writing a stream of bytes. It is mostly used to save a recordset in an XML format, to send commands to an OLE DB provider as an alternative to the CommandText object and to contain the contents of a binary or text file.

; Parameter

: A parameter is a means of altering the behaviour of a common piece of functionality, for instance a [[stored procedure]] might have different parameters passed to it depending on what needs to be done; these are called parameterised commands.

; Field

: Each Record object contains many fields, and a RecordSet object has a corresponding Field object also. The RecordSet object's Field object corresponds to a column in the database table that it references.

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=== ASP example ===

Here is an [[Active Server Pages|ASP]] example using ADO to select the "Name" field, from a table called "Phonebook", where a "PhoneNumber" was equal to "555-5555".

<sourcesyntaxhighlight lang=vb"vbscript">

dim myconnection, myrecordset, name

set myconnection = server.createobject("ADODB.Connection")

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set myrecordset = nothing

set myconnection = nothing

</syntaxhighlight>

</source>

This is equivalent to the following ASP code, which uses plain SQL instead of the functionality of the Recordset object:

<sourcesyntaxhighlight lang=vb"vbscript">

dim myconnection, myrecordset, name

set myconnection = server.createobject("ADODB.connection")

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set myrecordset = myconnection.execute("SELECT Name FROM Phonebook WHERE PhoneNumber = '555-5555'")

name = myrecordset(0)

</syntaxhighlight>

</source>

==Software support==

ADO is supported in any development language that supports binding to binary COM interfaces. These languages include ASP, [[Embarcadero Delphi |(programming language)|Delphi]], [[PowerBuilder]], and [[Visual Basic for Applications]] (VBA). ADO support has now been added to [[dBase]] Plus 8 (With ADO)

==Legacy==

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* [[ADO.NET]]

* [[Comparison of ADO and ADO.NET]]

* [[ActiveX]]

* [[MSDAIPP]]

==References==

{{Reflist}}

==External links==

* [http://msdn2.microsoft.com/en-us/library/ms805098.aspx Microsoft ADO page]

* [http://www.connectionstrings.com/ Database connection strings] {{Webarchive|url=https://web.archive.org/web/20210126200223/https://www.connectionstrings.com/ |date=January 26, 2021 }}

* [http://www.devguru.com/content/technologies/ado/home.html DevGuru ADO Quick Reference]

{{Microsoft APIs}}

{{Authority control}}

{{DEFAULTSORT:Activex Data Objects}}

[[Category:Microsoft application programming interfaces]]

[[Category:Data access technologies]]