Microsoft ActiveX Data Objects (ADO) | Microsoft Docs

Microsoft ActiveX Data Objects (ADO) | Microsoft Docs
Table of Contents
Microsoft ActiveX Data Objects (ADO)
New and recently updated articles
ADO Development Guide +
ADO Reference +
ADO Glossary
Microsoft ActiveX Data Objects (ADO)
3/14/2017 • 2 min to read • Edit Online
ActiveX Data Objects (ADO) consists of the following components:
ADO
Microsoft ActiveX Data Objects (ADO) enable your client applications to access and manipulate data from a variety
of sources through an OLE DB provider. Its primary benefits are ease of use, high speed, low memory overhead,
and a small disk footprint. ADO supports key features for building client/server and Web-based applications.
ADO MD
Microsoft ActiveX Data Objects (Multidimensional) (ADO MD) provides easy access to multidimensional data from
languages such as Microsoft Visual Basic, and Microsoft Visual C++. ADO MD extends Microsoft ActiveX Data
Objects (ADO) to include objects specific to multidimensional data, such as the CubeDef and Cellset objects. With
ADO MD you can browse multidimensional schema, query a cube, and retrieve the results.
Like ADO, ADO MD uses an underlying OLE DB provider to gain access to data. To work with ADO MD, the provider
must be a multidimensional data provider (MDP) as defined by the OLE DB for OLAP specification. MDPs present
data in multidimensional views as opposed to tabular data providers (TDPs) that present data in tabular views.
Refer to the documentation for your OLAP OLE DB provider for more detailed information about the specific syntax
and behaviors supported by your provider.
RDS
Remote Data Service (RDS) is a feature of ADO, with which you can move data from a server to a client application
or Web page, manipulate the data on the client, and return updates to the server in a single round trip.
IMPORTANT
Beginning with Windows 8 and Windows Server 2012, RDS server components are no longer included in the Windows
operating system (see Windows 8 and Windows Server 2012 Compatibility Cookbook for more detail). RDS client
components will be removed in a future version of Windows. Avoid using this feature in new development work, and plan to
modify applications that currently use this feature. Applications that use RDS should migrate to WCF Data Service.
ADOX
Microsoft ActiveX Data Objects Extensions for Data Definition Language and Security (ADOX) is an extension to the
ADO objects and programming model. ADOX includes objects for schema creation and modification, as well as
security. Because it is an object-based approach to schema manipulation, you can write code that will work against
various data sources regardless of differences in their native syntaxes.
ADOX is a companion library to the core ADO objects. It exposes additional objects for creating, modifying, and
deleting schema objects, such as tables and procedures. It also includes security objects to maintain users and
groups and to grant and revoke permissions on objects.
Documentation
ADO Security Design Issues
ADO Programmer's Guide
An introduction to using ADO, RDS, ADO MD, and ADOX.
ADO Programmer's Reference
This section of the ADO documentation contains topics for each ADO, RDS, ADO MD, and ADOX object, collection,
property, dynamic property, method, event, and enumeration.
ADO Glossary
Support
For free help with ADO issues, try posting to the ADO public newsgroup. This newsgroup is monitored by Microsoft
Product Support Services (PSS) support professionals who cover ADO, and by other experienced ADO developers.
Further information about support options can be found on the Microsoft Help and Support Web site.
New and Recently Updated: ActiveX Data Objects
(ADO) for SQL Server
7/18/2017 • 2 min to read • Edit Online
Nearly every day Microsoft updates some of its existing articles on its Docs.Microsoft.com documentation website.
This article displays excerpts from recently updated articles. Links to new articles might also be listed.
This article is generated by a program that is rerun periodically. Occasionally an excerpt can appear with imperfect
formatting, or as markdown from the source article. Images are never displayed here.
Recent updates are reported for the following date range and subject:
Date range of updates: 2017-05-23 -to- 2017-07-17
Subject area: ActiveX Data Objects (ADO) for SQL Server.
New Articles Created Recently
The following links jump to new articles which have been added recently.
There are no new articles to list, this time.
Compact List of Articles Updated Recently
This compact list provides links to all the updated articles which are listed in the Excerpts section.
Updated Articles with Excerpts
This section displays the excerpts of updates gathered from articles which have recently experienced a large update.
The excerpts displayed here appear separated from their proper semantic context. Also, sometimes an excerpt is
separated from important markdown syntax that surrounds it in the actual article. Therefore these excerpts are for
general guidance only. The excerpts only enable you to know whether your interests warrant taking the time to
click and visit the actual article.
For these and other reasons, do not copy code from these excerpts, and do not take as exact truth any text excerpt.
Instead, visit the actual article.
No articles in this area were updated recently, this time.
Similar Articles
This section lists very similar articles for recently updated articles in other subject areas, within the same
GitHub.com repository: MicrosoftDocs/sql-docs-pr.
Subject areas which do have new or recently updated articles
New + Updated (4+4) : Advanced Analytics for SQL docs
New + Updated (2+0) : Analysis Services for SQL docs
New + Updated (1+2) : Connect to SQL docs
New + Updated (6+0) : Database Engine for SQL docs
New + Updated (13+2): Linux for SQL docs
New + Updated (1+0) : Master Data Services (MDS) for SQL docs
New + Updated (1+0) : ODBC (Open Database Connectivity) for SQL docs
New + Updated (8+4) : Relational Databases for SQL docs
New + Updated (2+2) : Microsoft SQL Server docs
New + Updated (0+1) : SQL Server Management Studio (SSMS) docs
New + Updated (1+0) : Transact-SQL docs
New + Updated (1+0) : Tools for SQL docs
Subject areas which have no new or recently updated articles
New + Updated (0+0): ActiveX Data Objects (ADO) for SQL docs
New + Updated (0+0): Data Quality Services for SQL docs
New + Updated (0+0): Data Mining Extensions (DMX) for SQL docs
New + Updated (0+0): Integration Services for SQL docs
New + Updated (0+0): Multidimensional Expressions (MDX) for SQL docs
New + Updated (0+0): PowerShell for SQL docs
New + Updated (0+0): Reporting Services for SQL docs
New + Updated (0+0): Samples for SQL docs
New + Updated (0+0): SQL Server Data Tools (SSDT) docs
New + Updated (0+0): SQL Server Migration Assistant (SSMA) docs
New + Updated (0+0): XQuery for SQL docs
ADO Programmer's Guide for using ADO Objects
3/14/2017 • 1 min to read • Edit Online
This documentation provides an overview of how to use ADO objects to work with data from various data sources.
First, the introduction summarizes the new features and the requirement for installing, using, and redistributing the
ADO component. The next sections discuss the use of the various types of ADO objects. Finally, the appendixes
discuss various Microsoft-supplied data and service providers, error messages, and tips about how to use ADO in
several programming languages, in addition to samples and a glossary.
This section contains the following topics.
Introduction
ActiveX Data Objects (ADO)
Remote Data Services (RDS)
ADO (Multidimensional) (ADO MD)
ADO Extensions for Data Definition Language and Security (ADOX)
Appendixes
ADO Glossary
3/14/2017 • 17 min to read • Edit Online
This topic defines terms relevant to ADO.
A
absolute URL
A fully-qualified URL that specifies the location of a resource that resides on the Internet or an intranet. See also
URL and relative URL.
ActiveX control
Self-registering, in-process COM component that often has a visual element either at design time or run time.
ActiveX controls also have the ability to communicate with an Active Document container, such as Microsoft
Internet Explorer.
ADISAPI (Advanced Data Internet Server Application Programming Interface)
An ISAPI DLL that provides parsing, Automation control, Recordset marshaling, and MIME packaging. The ADISAPI
component works through the API provided by Internet Information Services (IIS). See also ISAPI.
aggregate function
In a query, a function such as COUNT, AVG, or STDEV that calculates a value using all the rows in a column of a
table. In writing expressions and in programming, you can use SQL aggregate functions (including the three listed
above) and domain aggregate functions to determine various statistics.
alias
An alternate name you give to a column or expression in an SQL SELECT statement, often shorter or more
meaningful. For example, BobSales is the alias in the following SELECT statement: "Select wr-Sales as BobSales
from SalesDB". An alias can be used to dynamically assign columns to control bindings on the DataControl object.
apartment threading
A COM threading model where all calls to an object occur on one thread. In apartment threading, COM
synchronizes and marshals calls. See also COMmddefcom.
asynchronous operation
An operation that returns control to the calling program without waiting for the operation to complete. Before the
operation is complete, code execution continues. See also synchronous operation.
B
binding entry
A mapping between a field in a table and a variable. In the ADO Visual C++ extensions, Recordset fields are
mapped to C/C++ variables.
bitmask
A numeric value intended for a bit-by-bit value comparison with other numeric values, typically to flag options in
parameter or return values. Usually this comparison is done with bitwise logical operators, such as And and Or in
Visual Basic, & and | in C++.
For example, the ADO FieldAttributeEnum values can be used as bitmasks to determine the attributes of a field.
Suppose you wanted to determine if a field was updateable. You could test for this with the following expression in
Visual Basic: Field.Attributes AND adFldUpdatable
If the result is TRUE, then the field is updateable.
bookmark
A marker that uniquely identifies a row within a set of rows so that a user can quickly navigate to it.
business object
An object that performs a defined set of operations, such as data validation or business rule logic. Business objects
usually reside on the middle tier.
business rule
The combination of validation edits, logon verifications, database lookups, policies, and algorithmic transformations
that constitute an enterprise's way of doing business. Also known as business logic.
C
calculated expression
An expression that is not constant, but whose value depends upon other values. To be evaluated, a calculated
expression must obtain and compute values from other sources, typically in other fields or rows.
chapter
A reference to a range of rows from a data source. In ADO, a chapter is typically a reference to another Recordset.
Chapter columns make it possible to define a parent-child relationship where the parent is the Recordset
containing the chapter column and the child is the Recordset represented by the chapter.
chapter-alias
An alias that refers to the column appended to the parent.
character set
A mapping of a set of characters to their numeric values. For example, Unicode is a 16-bit character set capable of
encoding all known characters and used as a worldwide character-encoding standard.
child
The dependant side of a hierarchical relationship. A child is a node in a hierarchical structure that has another node
above it (closer to the root). See also child-alias, parent-child relationship, parent.
child-alias
An alias that refers to the child. See also alias, child.
CLSID (class identifier)
A universally unique identifier (UUID) that identifies a COM component. Each COM component has its CLSID in the
Windows Registry so that it can be loaded by other applications. See also ProgID, COM.
client tier
A logical layer of a distributed system that typically presents data to and processes input from the user, sometimes
referred to as the front end. Usually, the client tier requests data from a server based on input, and then formats
and displays the result. See also middle tier, data source tier, distributed application.
COM (Component Object Model)
A binary standard that enables objects to interoperate in a networked environment regardless of the language in
which they were developed or on which computers they reside. COM-based technologies include ActiveX Controls,
Automation, and object linking and embedding (OLE). COM allows an object to expose its functionality to other
components and to host applications. It defines both how the object exposes itself and how this exposure works
across processes and across networks. COM also defines the object's life cycle.
COM component
Binary file — such as .dll, .ocx, and some .exe files — that supports the COM standard for providing objects. Such a
file contains code for one or more class factories, COM classes, registry-entry mechanisms, loading code, and so on.
comparison operator
An operator that compares two expressions and returns a Boolean value.
A criteria parameter that may be expressed as ">" (greater than), "<" (less than), "=" (equal), ">=" (greater than or
equal), "<=" (less than or equal), "<>" (not equal), or "like" (pattern matching).
component
An object that encapsulates both data and code, and provides a well-specified set of publicly available services.
compound file
An implementation of COM structured storage for files. A compound file stores separate objects in a single,
structured file consisting of two main elements: storage objects and stream objects. Together, they function like a
file system within a file.
A number of individual files bound together in one physical file. Each individual file in a compound file can be
accessed as if it were a single physical file.
constant
A numeric or string value that does not change. Named ADO enumerations (enumerated constants) can be used in
your code instead of actual values, for example, adUseClient is a constant whose value is 3. (Const adUseClient =
3). See also enumeration.
cursor
A database element that controls record navigation, updateability of data, and the visibility of changes made to the
database by other users.
D
data binding
The process of associating the objects or controls of an application to a data source. A control associated with a
data source is called a data-bound control.
The contents of a data-bound control are associated with values from a database. For example, a grid control that is
bound to a Recordset object can be updated when the rows in the Recordset are updated. When new values are
retrieved by the Recordset, new values are displayed in the grid.
data provider
Software that exposes data to an ADO application either directly or via a service provider. See also service provider.
data shaping
A technique which makes use of a formalized syntax (called Shape language) to define a specialized Recordset
object (called a shaped Recordset) that contains not just data, but also references to other Recordset objects and/or
computed values based on those other Recordset objects.
data source tier
A logical layer of a distributed system that represents a computer running a DBMS, such as an SQL Server
database. See also client tier, middle tier, distributed application.
DCOM
A wire protocol that enables COM components to communicate directly with each other across a network. See also
COM, component.
DDL (Data Definition Language)
Those statements in SQL that define, as opposed to manipulate, data. The schema of a database is created or
modified with DDL. For example, CREATE TABLE, CREATE INDEX, GRANT, and REVOKE are SQL DDL statements.
default stream
A text or binary stream (represented by a Stream object) that is associated with Record or Recordset objects
when using certain OLE DB providers, such as the Microsoft OLE DB Provider for Internet Publishing. The default
stream typically contains the contents of a file such as the HTML code for the root of a Web site.
distributed application
A program written so that the processing can be divided across multiple computers over a network. Typically, a
distributed application is divided into presentation, business logic, and data store layers, or tiers. See also client tier,
middle tier, data source tier.
disconnected Recordset
A Recordset object in a client cache that no longer has a live connection to the server. If the original data source
needs to be accessed again for some reason, such as updating data, the connection must be re-established.
However, the collections, properties, and methods of a disconnected Recordset can still be accessed.
DML (Data Manipulation Language)
Those statements in SQL that manipulate, as opposed to define, data. The values in a database are selected and
modified with DML. For example, INSERT, UPDATE, DELETE, and SELECT are SQL DML statements.
document source provider
A special class of providers that manage folders and documents. When a document is represented by a Record
object, or a folder of documents is represented by a Recordset object, the document source provider populates
those objects with a unique set of fields that describe characteristics of the document, instead of the actual
document itself. See also resource record.
DSN (data source name)
The collection of information used to connect your application to a particular ODBC database. The ODBC Driver
Manager uses this information to create a connection to the database. A DSN can be stored in a file (a file DSN) or
in the Windows Registry (a machine DSN).
dynamic property
A property specific to a data provider or the cursor service. The Properties collection of an object is populated with
these automatically ("dynamically"). An object has no dynamic properties until it is connected to a data source
through a particular data provider. See also data provider, cursor.
E
Enumeration
A list of named constants. Enumerated values need not be unique. However the name of each value must be unique
within the scope where the enumeration is defined. In ADO, enumerations are used for numeric parameter and
return values, to add meaning to ADO code and to shield the developer from the numeric values (which may
change from version to version). For example, to open a static Recordset, use the adOpenStatic enumerated
value: Recordset.Open ,,adOpenStatic
Also referred to as enumerated constant. See also constant.
event
An action recognized by an object, for which you can write code to respond. Events can be generated by command
execution, transaction completion, recordset navigation, and data updates, among other actions. See also event
handler.
event handler
An event handler is the code that is executed when an event occurs. See also event.
H
handler
A routine that manages a common and relatively simple condition or operation, such as error recovery or data
management.
hierarchical Recordset
A Recordset that contains another Recordset. See also data shaping, chapter.
For more information, see Accessing Rows in a Hierarchical Recordset.
hierarchy
In general, a hierarchy is a ranked structure with a top level and subordinate levels. In ADO, hierarchical Recordsets
are used to represent the parent-child relationship between a record and a chapter. Also in ADO, Record and
Stream objects can be used to access hierarchical tree structures such as a folder and documents. ADO MD also
includes Hierarchy objects to represent a relationship between the levels of a dimension in an OLAP cube. See also
hierarchical Recordsets, parent-child relationship, chapter, tree.
I-L
ISAPI (Internet Server Application Programming Interface)
A set of functions for Internet servers, such as a Windows NT® Server/Windows 2000 Server running Microsoft®
Internet Information Services (IIS).
Key
A column or columns in a table that uniquely identify a row; often used to index a table.
M
marshaling
The process of packaging, sending, and unpackaging interface method parameters across thread or process
boundaries.
middle tier
The logical layer in a distributed system between a user interface or Web client and the database. This is typically
where business objects are instantiated. The middle tier is a collection of business rules and functions that generate
and operate upon receiving information. They accomplish this through business rules, which can change frequently,
and are thus encapsulated into components that are physically separate from the application logic itself. Also
known as application server tier. See also distributed application, client tier, data source tier.
MIME (Multi-purpose Internet Mail Extension)
An Internet protocol originally developed to allow exchange of electronic mail messages with rich content across
heterogeneous network, machine, and e-mail environments. In practice, MIME has also been adopted and extended
by non-mail applications.
MIME is a standard that allows binary data to be published and read on the Internet. The header of a file with binary
data contains the MIME type of the data; this informs client programs (Web browsers and mail packages, for
instance) that they will need to handle the data in a different way than they handle straight text. For example, the
header of a Web document containing a JPEG graphic contains the MIME type specific to the JPEG file format. This
allows a browser to display the file with its JPEG viewer, if one is present.
N-O
node
An element in a hierarchical tree structure. A node may be the root, or the child of another node. A node can also be
the parent of multiple children. See also hierarchy, tree, root, child, parent.
object variable
A variable that contains a reference to an object. For example, objCustomObject is a variable that points to an object
of type CustomObject: Set objCustomObject = CreateObject(adodb.Recordset)
ODBC (Open Database Connectivity)
A standard programming language interface used to connect to a variety of data sources. This is usually accessed
through Control Panel, where data source names (DSNs) can be assigned to use specific ODBC drivers.
OLE DB
A set of interfaces that expose data from a variety of sources using COM. OLE DB interfaces provide applications
with uniform access to data stored in diverse information sources. These interfaces support the amount of DBMS
functionality appropriate to the data source, enabling it to share its data. See also COM.
optimistic locking
A type of locking in which the data page containing one or more records, including the record being edited, is
unavailable to other users only while the record is being updated by the Update method, but is available before
and after the call to Update.
Optimistic locking is used when the Recordset object is opened with the LockType parameter or property set to
adLockOptimistic or adLockBatchOptimistic. See also pessimistic locking.
ordinal value
The numeric location of an item within an order. In an ADO collection, the ordinal value of the first item is zero (0).
The next item is one (1), and so on.
P
parameterized command
A query or command that allows you to set parameter values before the command is executed. For example, a SQL
string can be parameterized by embedding parameter markers in the SQL string (designated by the '?' character).
The application then specifies values for each parameter and executes the command.
parent
The controlling side of a hierarchical relationship. In a hierarchical structure, a parent has one or more child nodes
directly beneath it in the hierarchy. See also parent-alias, parent-child relationship, child.
parent-alias
An alias that refers to the parent. See also alias, parent.
parent-child relationship
A relationship in a hierarchical structure in which the parent is one level higher and directly associated with one or
more children. A child is one level lower and must have one parent. See also parent, child.
pessimistic locking
A type of locking in which the page containing one or more records, including the record being edited, is
unavailable to other users to ensure that an update will be made. Pessimistic locking behavior is defined by the OLE
DB provider. Typically, records are locked upon editing and remain unavailable until the Update method has
completed.
Pessimistic locking is enabled when the Recordset object is opened with the LockType parameter or property set
to adLockPessimistic. See also optimistic locking.
pooling
A performance optimization based on using collections of pre-allocated resources, such as objects or database
connections. It is more efficient to draw an existing resource from the pool than to create a new resource.
ProgID (programmatic identifier)
A unique name mapped to the Windows registry by a COM application. The ProgID for an ADO Connection is
"ADODB.Connection". See also CLSID, COM.
proxy
An interface-specific object that provides the parameter marshaling and communication required for a client to call
an application object that is running in a different execution environment, such as on a different thread or in
another process. The proxy is located with the client and communicates with a corresponding stub that is located
with the application object that is being called. See also stub.
R
relative URL
A partially qualified URL that specifies a resource on the Internet or an intranet whose location is relative to a
starting point specified by an absolute URL or equivalent ADO Connection object. In effect, the concatenated
absolute and relative URLs consitute a complete URL. See also URL and absolute URL.
remote data source
A data source that exists on a another computer, rather than on the local system (where the client application runs).
resource record
A record from a document source provider that contains fields for the definition and description of a folder or
document. The document itself is not contained in the resource record but typically can be accessed by the default
stream or a field in the resource record containing a URL. See also document source provider, default stream, URL.
rowset
A set of rows from a data source, all having the same field schema. A rowset can represent all or some fields from a
table. A rowset can also represent a virtual table, created by a query or a join of two or more tables. In ADO, rowsets
are represented by Recordset objects.
S
Scope
The range of reference for an object or variable or a range of records in a view or table. For example, local variables
can be referenced only within the procedure in which they were defined. Public variables are accessible from
anywhere in the application. Objects, such as the current database, are in scope if they are in the defined search
path. Record ranges can be specified with a Scope clause in many commands.
service provider
Software that encapsulates a service by producing and consuming data, augmenting features in your ADO
applications. It is a provider that does not directly expose data, rather it provides a service, such as query
processing. The service provider may process data provided by a data provider. See also data provider.
shaped Recordset
A Recordset whose columns have been specifically defined to contain not just data, but also references (called
chapters) to other Recordset objects and/or computed values based on other Recordset objects.
sibling
Any two or more nodes in a hierarchical structure that are on the same level in the hierarchy. The root node in a
hierarchy has no siblings.
stored procedure
A precompiled collection of code such as SQL statements and optional control-of-flow statements stored under a
name and processed as a unit. Stored procedures are stored within a database; they can be executed with one call
from an application and allow user-declared variables, conditional execution, and other powerful programming
features.
stub
An interface-specific object that provides the parameter marshaling and communication required for an application
object to receive calls from a client that is running in a different execution environment, such as on a different
thread or in another process. The stub is located with the application object and communicates with a
corresponding proxy that is located with the client that calls it. See also proxy.
sub-node
See child.
synchronous operation
An operation initiated by code that completes before the next operation may start. See also asynchronous
operation.
T-Z
Tree
A structure representing a hierarchical relationship between elements (nodes). There is one node at the top level of
a tree (the root). Underneath the root, there can be multiple children. Each child may in turn be the parent of other
children, thus branching like a tree. A folder containing documents and other folders is a typical example of a tree
structure. See also hierarchy, node, root, child, parent.
Web server
A computer that provides Web services and pages to intranet and Internet users.
ADO Glossary Terms
3/14/2017 • 17 min to read • Edit Online
This topic defines terms relevant to ADO.
A
absolute URL A fully-qualified URL that specifies the location of a resource that resides on the Internet or an
intranet. See also URL and relative URL.
ActiveX control Self-registering, in-process COM component that often has a visual element either at design time or
run time. ActiveX controls also have the ability to communicate with an Active Document container, such as
Microsoft Internet Explorer.
ADISAPI (Advanced Data Internet Server Application Programming Interface) An ISAPI DLL that provides parsing,
Automation control, Recordset marshaling, and MIME packaging. The ADISAPI component works through the API
provided by Internet Information Services (IIS). See also ISAPI.
aggregate function In a query, a function such as COUNT, AVG, or STDEV that calculates a value using all the rows
in a column of a table. In writing expressions and in programming, you can use SQL aggregate functions (including
the three listed above) and domain aggregate functions to determine various statistics.
alias An alternate name you give to a column or expression in an SQL SELECT statement, often shorter or more
meaningful. For example, BobSales is the alias in the following SELECT statement: "Select wr-Sales as BobSales
from SalesDB". An alias can be used to dynamically assign columns to control bindings on the DataControl object.
apartment threading A COM threading model where all calls to an object occur on one thread. In apartment
threading, COM synchronizes and marshals calls. See also COMmddefcom.
asynchronous operation An operation that returns control to the calling program without waiting for the operation
to complete. Before the operation is complete, code execution continues. See also synchronous operation.
B
binding entry A mapping between a field in a table and a variable. In the ADO Visual C++ extensions, Recordset
fields are mapped to C/C++ variables.
bitmask A numeric value intended for a bit-by-bit value comparison with other numeric values, typically to flag
options in parameter or return values. Usually this comparison is done with bitwise logical operators, such as And
and Or in Visual Basic, & and | in C++.
For example, the ADO FieldAttributeEnum values can be used as bitmasks to determine the attributes of a field.
Suppose you wanted to determine if a field was updateable. You could test for this with the following expression in
Visual Basic: Field.Attributes AND adFldUpdatable
If the result is TRUE, then the field is updateable.
bookmark A marker that uniquely identifies a row within a set of rows so that a user can quickly navigate to it.
business object An object that performs a defined set of operations, such as data validation or business rule logic.
Business objects usually reside on the middle tier.
business rule The combination of validation edits, logon verifications, database lookups, policies, and algorithmic
transformations that constitute an enterprise's way of doing business. Also known as business logic.
C
calculated expression An expression that is not constant, but whose value depends upon other values. To be
evaluated, a calculated expression must obtain and compute values from other sources, typically in other fields or
rows.
chapter A reference to a range of rows from a data source. In ADO, a chapter is typically a reference to another
Recordset.
Chapter columns make it possible to define a parent-child relationship where the parent is the Recordset
containing the chapter column and the child is the Recordset represented by the chapter.
chapter-alias An alias that refers to the column appended to the parent.
character set A mapping of a set of characters to their numeric values. For example, Unicode is a 16-bit character
set capable of encoding all known characters and used as a worldwide character-encoding standard.
child The dependant side of a hierarchical relationship. A child is a node in a hierarchical structure that has another
node above it (closer to the root). See also child-alias, parent-child relationship, parent.
child-alias An alias that refers to the child. See also alias, child.
CLSID (class identifier) A universally unique identifier (UUID) that identifies a COM component. Each COM
component has its CLSID in the Windows Registry so that it can be loaded by other applications. See also ProgID,
COM.
client tier A logical layer of a distributed system that typically presents data to and processes input from the user,
sometimes referred to as the front end. Usually, the client tier requests data from a server based on input, and then
formats and displays the result. See also middle tier, data source tier, distributed application.
COM (Component Object Model) A binary standard that enables objects to interoperate in a networked
environment regardless of the language in which they were developed or on which computers they reside. COMbased technologies include ActiveX Controls, Automation, and object linking and embedding (OLE). COM allows an
object to expose its functionality to other components and to host applications. It defines both how the object
exposes itself and how this exposure works across processes and across networks. COM also defines the object's
life cycle.
COM component Binary file — such as .dll, .ocx, and some .exe files — that supports the COM standard for
providing objects. Such a file contains code for one or more class factories, COM classes, registry-entry
mechanisms, loading code, and so on.
comparison operator An operator that compares two expressions and returns a Boolean value.
A criteria parameter that may be expressed as ">" (greater than), "<" (less than), "=" (equal), ">=" (greater than or
equal), "<=" (less than or equal), "<>" (not equal), or "like" (pattern matching).
component An object that encapsulates both data and code, and provides a well-specified set of publicly available
services.
compound file An implementation of COM structured storage for files. A compound file stores separate objects in a
single, structured file consisting of two main elements: storage objects and stream objects. Together, they function
like a file system within a file.
A number of individual files bound together in one physical file. Each individual file in a compound file can be
accessed as if it were a single physical file.
constant A numeric or string value that does not change. Named ADO enumerations (enumerated constants) can
be used in your code instead of actual values, for example, adUseClient is a constant whose value is 3. (Const
adUseClient = 3). See also enumeration.
cursor A database element that controls record navigation, updateability of data, and the visibility of changes made
to the database by other users.
D
data binding The process of associating the objects or controls of an application to a data source. A control
associated with a data source is called a data-bound control.
The contents of a data-bound control are associated with values from a database. For example, a grid control that is
bound to a Recordset object can be updated when the rows in the Recordset are updated. When new values are
retrieved by the Recordset, new values are displayed in the grid.
data provider Software that exposes data to an ADO application either directly or via a service provider. See also
service provider.
data shaping A technique which makes use of a formalized syntax (called Shape language) to define a specialized
Recordset object (called a shaped Recordset) that contains not just data, but also references to other Recordset
objects and/or computed values based on those other Recordset objects.
data source tier A logical layer of a distributed system that represents a computer running a DBMS, such as an SQL
Server database. See also client tier, middle tier, distributed application.
DCOM A wire protocol that enables COM components to communicate directly with each other across a network.
See also COM, component.
DDL (Data Definition Language) Those statements in SQL that define, as opposed to manipulate, data. The schema
of a database is created or modified with DDL. For example, CREATE TABLE, CREATE INDEX, GRANT, and
REVOKE are SQL DDL statements.
default stream A text or binary stream (represented by a Stream object) that is associated with Record or
Recordset objects when using certain OLE DB providers, such as the Microsoft OLE DB Provider for Internet
Publishing. The default stream typically contains the contents of a file such as the HTML code for the root of a Web
site.
distributed application A program written so that the processing can be divided across multiple computers over a
network. Typically, a distributed application is divided into presentation, business logic, and data store layers, or
tiers. See also client tier, middle tier, data source tier.
disconnected Recordset A Recordset object in a client cache that no longer has a live connection to the server. If
the original data source needs to be accessed again for some reason, such as updating data, the connection must
be re-established. However, the collections, properties, and methods of a disconnected Recordset can still be
accessed.
DML (Data Manipulation Language) Those statements in SQL that manipulate, as opposed to define, data. The
values in a database are selected and modified with DML. For example, INSERT, UPDATE, DELETE, and SELECT are
SQL DML statements.
document source provider A special class of providers that manage folders and documents. When a document is
represented by a Record object, or a folder of documents is represented by a Recordset object, the document
source provider populates those objects with a unique set of fields that describe characteristics of the document,
instead of the actual document itself. See also resource record.
DSN (data source name) The collection of information used to connect your application to a particular ODBC
database. The ODBC Driver Manager uses this information to create a connection to the database. A DSN can be
stored in a file (a file DSN) or in the Windows Registry (a machine DSN).
dynamic property A property specific to a data provider or the cursor service. The Properties collection of an object
is populated with these automatically ("dynamically"). An object has no dynamic properties until it is connected to a
data source through a particular data provider. See also data provider, cursor.
E
Enumeration A list of named constants. Enumerated values need not be unique. However the name of each value
must be unique within the scope where the enumeration is defined. In ADO, enumerations are used for numeric
parameter and return values, to add meaning to ADO code and to shield the developer from the numeric values
(which may change from version to version). For example, to open a static Recordset, use the adOpenStatic
enumerated value: Recordset.Open ,,adOpenStatic
Also referred to as enumerated constant. See also constant.
event An action recognized by an object, for which you can write code to respond. Events can be generated by
command execution, transaction completion, recordset navigation, and data updates, among other actions. See also
event handler.
event handler An event handler is the code that is executed when an event occurs. See also event.
H
handler A routine that manages a common and relatively simple condition or operation, such as error recovery or
data management.
hierarchical Recordset A Recordset that contains another Recordset. See also data shaping, chapter.
For more information, see Accessing Rows in a Hierarchical Recordset.
hierarchy In general, a hierarchy is a ranked structure with a top level and subordinate levels. In ADO, hierarchical
Recordsets are used to represent the parent-child relationship between a record and a chapter. Also in ADO,
Record and Stream objects can be used to access hierarchical tree structures such as a folder and documents. ADO
MD also includes Hierarchy objects to represent a relationship between the levels of a dimension in an OLAP cube.
See also hierarchical Recordsets, parent-child relationship, chapter, tree.
I-L
ISAPI (Internet Server Application Programming Interface) A set of functions for Internet servers, such as a
Windows NT® Server/Windows 2000 Server running Microsoft® Internet Information Services (IIS).
Key A column or columns in a table that uniquely identify a row; often used to index a table.
M
marshaling The process of packaging, sending, and unpackaging interface method parameters across thread or
process boundaries.
middle tier The logical layer in a distributed system between a user interface or Web client and the database. This is
typically where business objects are instantiated. The middle tier is a collection of business rules and functions that
generate and operate upon receiving information. They accomplish this through business rules, which can change
frequently, and are thus encapsulated into components that are physically separate from the application logic itself.
Also known as application server tier. See also distributed application, client tier, data source tier.
MIME (Multi-purpose Internet Mail Extension) An Internet protocol originally developed to allow exchange of
electronic mail messages with rich content across heterogeneous network, machine, and e-mail environments. In
practice, MIME has also been adopted and extended by non-mail applications.
MIME is a standard that allows binary data to be published and read on the Internet. The header of a file with binary
data contains the MIME type of the data; this informs client programs (Web browsers and mail packages, for
instance) that they will need to handle the data in a different way than they handle straight text. For example, the
header of a Web document containing a JPEG graphic contains the MIME type specific to the JPEG file format. This
allows a browser to display the file with its JPEG viewer, if one is present.
N-O
node An element in a hierarchical tree structure. A node may be the root, or the child of another node. A node can
also be the parent of multiple children. See also hierarchy, tree, root, child, parent.
object variable A variable that contains a reference to an object. For example, objCustomObject is a variable that
points to an object of type CustomObject: Set objCustomObject = CreateObject(adodb.Recordset)
ODBC (Open Database Connectivity) A standard programming language interface used to connect to a variety of
data sources. This is usually accessed through Control Panel, where data source names (DSNs) can be assigned to
use specific ODBC drivers.
OLE DB A set of interfaces that expose data from a variety of sources using COM. OLE DB interfaces provide
applications with uniform access to data stored in diverse information sources. These interfaces support the
amount of DBMS functionality appropriate to the data source, enabling it to share its data. See also COM.
optimistic locking A type of locking in which the data page containing one or more records, including the record
being edited, is unavailable to other users only while the record is being updated by the Update method, but is
available before and after the call to Update.
Optimistic locking is used when the Recordset object is opened with the LockType parameter or property set to
adLockOptimistic or adLockBatchOptimistic. See also pessimistic locking.
ordinal value The numeric location of an item within an order. In an ADO collection, the ordinal value of the first
item is zero (0). The next item is one (1), and so on.
P
parameterized command A query or command that allows you to set parameter values before the command is
executed. For example, a SQL string can be parameterized by embedding parameter markers in the SQL string
(designated by the '?' character). The application then specifies values for each parameter and executes the
command.
parent The controlling side of a hierarchical relationship. In a hierarchical structure, a parent has one or more child
nodes directly beneath it in the hierarchy. See also parent-alias, parent-child relationship, child.
parent-alias An alias that refers to the parent. See also alias, parent.
parent-child relationship A relationship in a hierarchical structure in which the parent is one level higher and
directly associated with one or more children. A child is one level lower and must have one parent. See also parent,
child.
pessimistic locking A type of locking in which the page containing one or more records, including the record being
edited, is unavailable to other users to ensure that an update will be made. Pessimistic locking behavior is defined
by the OLE DB provider. Typically, records are locked upon editing and remain unavailable until the Update
method has completed.
Pessimistic locking is enabled when the Recordset object is opened with the LockType parameter or property set
to adLockPessimistic. See also optimistic locking.
pooling A performance optimization based on using collections of pre-allocated resources, such as objects or
database connections. It is more efficient to draw an existing resource from the pool than to create a new resource.
ProgID (programmatic identifier) A unique name mapped to the Windows registry by a COM application. The
ProgID for an ADO Connection is "ADODB.Connection". See also CLSID, COM.
proxy An interface-specific object that provides the parameter marshaling and communication required for a client
to call an application object that is running in a different execution environment, such as on a different thread or in
another process. The proxy is located with the client and communicates with a corresponding stub that is located
with the application object that is being called. See also stub.
R
relative URL A partially qualified URL that specifies a resource on the Internet or an intranet whose location is
relative to a starting point specified by an absolute URL or equivalent ADO Connection object. In effect, the
concatenated absolute and relative URLs consitute a complete URL. See also URL and absolute URL.
remote data source A data source that exists on a another computer, rather than on the local system (where the
client application runs).
resource record A record from a document source provider that contains fields for the definition and description of
a folder or document. The document itself is not contained in the resource record but typically can be accessed by
the default stream or a field in the resource record containing a URL. See also document source provider, default
stream, URL.
rowset A set of rows from a data source, all having the same field schema. A rowset can represent all or some fields
from a table. A rowset can also represent a virtual table, created by a query or a join of two or more tables. In ADO,
rowsets are represented by Recordset objects.
S
Scope The range of reference for an object or variable or a range of records in a view or table. For example, local
variables can be referenced only within the procedure in which they were defined. Public variables are accessible
from anywhere in the application. Objects, such as the current database, are in scope if they are in the defined
search path. Record ranges can be specified with a Scope clause in many commands.
service provider Software that encapsulates a service by producing and consuming data, augmenting features in
your ADO applications. It is a provider that does not directly expose data, rather it provides a service, such as query
processing. The service provider may process data provided by a data provider. See also data provider.
shaped Recordset A Recordset whose columns have been specifically defined to contain not just data, but also
references (called chapters) to other Recordset objects and/or computed values based on other Recordset objects.
sibling Any two or more nodes in a hierarchical structure that are on the same level in the hierarchy. The root node
in a hierarchy has no siblings.
stored procedure A precompiled collection of code such as SQL statements and optional control-of-flow statements
stored under a name and processed as a unit. Stored procedures are stored within a database; they can be executed
with one call from an application and allow user-declared variables, conditional execution, and other powerful
programming features.
stub An interface-specific object that provides the parameter marshaling and communication required for an
application object to receive calls from a client that is running in a different execution environment, such as on a
different thread or in another process. The stub is located with the application object and communicates with a
corresponding proxy that is located with the client that calls it. See also proxy.
sub-node See child.
synchronous operation An operation initiated by code that completes before the next operation may start. See also
asynchronous operation.
T-Z
Tree A structure representing a hierarchical relationship between elements (nodes). There is one node at the top
level of a tree (the root). Underneath the root, there can be multiple children. Each child may in turn be the parent of
other children, thus branching like a tree. A folder containing documents and other folders is a typical example of a
tree structure. See also hierarchy, node, root, child, parent.
Web server A computer that provides Web services and pages to intranet and Internet users.
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertising