Visual Basic 6 Database How-To

Previous chapterNext chapterContents


- D -

ACTIVEX DATA OBJECTS REFERENCE


The ActiveX Data Objects provide you with an interface to OLE DB data sources. Figure D.1 shows the entire ADO object model.

Figure D.1. The ActiveX Data Objects object model.

This appendix is designed as a reference to all the objects that are included in the ADO object model. The collections and objects are listed in alphabetical order with tables indicating and describing all the methods and properties available to each.

Command Object

The Command object contains the properties and methods necessary to execute SQL commands using ADO. Tables D.1 and D.2 summarize the methods and properties of the Command object.

Table D.1. Command Object Methods

METHOD Description
Cancel Cancels an asynchronously executing command
CreateParameter Creates a new Parameter object
Execute Executes the command

Table D.2. Command Object Properties

PROPERTY Description
ActiveConnection Returns or sets the active Connection object
CommandText Returns or sets the command text
CommandTimeout Returns or sets the timeout in seconds
CommandType Returns or sets the command type
Name Returns the name of the object
Parameters Returns the parameters for this command
Prepared Returns or sets whether to compile this command before executing
Properties Returns the dynamic properties of object
State Returns the current state of the object

Connection Object

The Connection object manages a data provider connection in ADO. Table D.3 describes the Connection object events, Table D.4 summarizes the Connection object methods, and Table D.5 lists the Connection object properties.

Table D.3. Connection Object Events

EVENT Description
BeginTransComplete Fired after the BeginTrans method is completed
CommitTransComplete Fired after the CommitTrans method is completed
ConnectComplete Fired after the Open method is completed
Disconnect Fired after the Close method is completed
ExecuteComplete Fired after the Execute method is completed
InfoMessage Fired when an information message comes from the data provider
RollbackTransComplete Fired after the RollbackTrans method is complete
WillConnect Fired before a connection is made
WillExecute Fired before the Execute method is performed

Table D.4. Connection Object Methods

METHOD Description
BeginTrans Begins a transaction
Cancel Cancels an asynchronous operation
Close Closes an object
Execute Executes a SQL statement or query
Open Open the connection
OpenSchema Returns a Recordset object filled with database information
RollbackTrans Rolls back a transaction

Table D.5. Connection Object Properties

PROPERTY Description
Attributes Indicates characteristics of the object
CommandTimeout Returns or sets the timeout for the Execute method
ConnectionString Returns or sets the connection string
ConnectionTimeout Returns or sets the timeout to establish a connection
CursorLocation Returns or sets where the cursor is created
DefaultDatabase Returns or sets the default database
Errors Returns the collection of Error objects raised by data providers
IsolationLevel Returns or set the level of isolation for transactions
Mode Returns the available permissions for modifying data
Properties Returns the dynamic properties for the object
Provider Returns the name of the data provider
State Returns the current state of the object
Version Returns the ADO version number

Errors Collection, Error Object

The Errors collection and Error object manage the data provider generated errors for a Connection object. Tables D.6 and D.7 list the methods and properties for the Errors collection. Table D.8 lists the properties for the Error object.

Table D.6. Errors Collection Methods

METHOD Description
Clear Clears the collection
Refresh Refreshes the items in the collection

Table D.7. Errors Collection Properties

PROPERTY Description
Count Returns the number of items in the collection
Item Returns the specified object from the collection

Table D.8. Error Object Properties

PROPERTY Description
Description Returns the description of the error
HelpContext Returns a Help Context Id if a HelpFile is available
HelpFile Returns the name of a help file where help on the error is available
NativeError Returns the error number reported by the underlying API or interface
Number Returns the error number
Source Returns the name of the source of the error
SQLState Returns the five-character ANSI standard error

Fields Collection, Field Object

The Fields collection and Field object are the columns or fields returned in a Recordset object. Table D.9 summarizes the methods of the Fields collection. Table D.10 describes the properties of the Fields collection. Tables D.11 and D.12 lists the methods and properties of the Field object.

Table D.9. Fields Collection Methods

METHOD Description
Append Appends an object to the collection
Delete Deletes an object from the collection
Refresh Refreshes the items in the collection

Table D.10. Fields Collection Properties

PROPERTY Description
Count Returns the number of items in the collection
Item Returns the specified object from the collection

Table D.11. Field Object Methods

METHOD Description
AppendChunk Appends data to the object's value
GetChunk Returns a portion of data from the object's value

Table D.12. Field Object Properties

PROPERTY Description
ActualSize Returns the size of the field
Attributes Indicates characteristics of the object
DataFormat Returns or sets the stdDataFormat object
DefinedSize The defined size of the field
Name The name of the object
NumericScale Returns or sets the number of decimal places to which numeric values will be resolved
OriginalValue Returns the values of the field when the Recordset was first opened
Precision Returns or sets the maximum number of digits used to represent values
Properties Returns the dynamic properties for the object
Type Returns the datatype
UnderlyingValue Returns the object's current value in the database
Value Returns the object's current value in the Recordset

Parameters Collection, Parameter Object

The Parameters collection and Parameter object are used with the Command object to execute stored procedures. Tables D.13 and D.14 list the methods and properties for the Parameters collection. Table D.15 lists the method for the Parameter object, and Table D.16 lists the properties of the Parameter object.

Table D.13. Parameters Collection Methods

METHOD Description
Append Appends an object to the collection
Delete Deletes an object from the collection
Refresh Refreshes the items in the collection

Table D.14. Parameters Collection Properties

PROPERTY Description
Count Returns the number of items in the collection
Item Returns the specified object from the collection

Table D.15. Parameter Object method

METHOD Description
AppendChunk Appends data to the object's value.

Table D.16. Parameter Object Properties

PROPERTY Description
Attributes Indicates characteristics of the object
Direction Returns or sets the direction of the parameter
Name The name of the object
NumericScale Returns or sets the number of decimal places to which numeric values will be resolved
Precision Returns or sets the maximum digits used to represent values
Properties Returns the dynamic properties for the object
Size Returns the maximum size of the object
Type Returns the datatype
Value Returns the object's value

Properties Collection, Property Object

The Properties collection and the Property object manage dynamic characteristics for an ADO object. Tables D.17 and D.18 list the methods and properties of the Properties collection. Table D.19 lists the properties of the Property object.

Table D.17. Properties Collection Method

METHOD Description
Refresh Refreshes the items in the collection

Table D.18. Properties Collection Properties

PROPERTY DESCRIPTION
Count Returns the number of items in the collection
Item Returns the specified object from the collection

Table D.19. Property Object Properties

PROPERTY Description
Attributes Indicates characteristics of the object
Name The name of the object
Type Returns the datatype
Value Returns the object's value

Recordset Object

The Recordset object handles the rows returned from an opened table or executed query. Tables D.20, D.21, and D.22 describe the events, methods, and properties of the Recordset object.

Table D.20. Recordset Object Events

EVENT Description
EndOfRecordset Fired when the end of the Recordset is reached
FetchComplete Fired when the entire Recordset is fetched
FetchProgress Fired to indicate the progress of the data fetch
FieldChangeComplete Fired after a field is changed
MoveComplete Fired after the Recordset moves to another record
RecordChangeComplete Fired after a record is changed
RecordsetChangeComplete Fired after the Recordset is changed
WillChangeField Fired before a field's value is changed
WillChangeRecord Fired before a record is changed.
WillChangeRecordset Fired before the Recordset is changed.
WillMove Fired before the Recordset moves to another record.

Table D.21. Recordset Object Methods

METHOD Description
AddNew Adds a new record to the object
Cancel Cancels an asynchronously executing command
CancelBatch Cancels changes before BatchUpdate has been called
CancelUpdate Cancels changes before an Update has been called
Clone Returns a duplicate Recordset
Close Closes the object
CompareBookmarks Compares two bookmarks
Delete Deletes from the Recordset
Find Finds a record in the Recordset
GetRows Retrieves records into an array
GetString Retrieves records into a string
Move Moves the position of the current record
MoveFirst Moves to the first record of the Recordset
MoveLast Moves to the last record of the Recordset
MoveNext Moves to the next record of the Recordset
MovePrevious Moves to the previous record of the Recordset
NextRecordset Clears current Recordset and moves to the next Recordset
Open Opens the object
Requery Refreshes the Recordset by re-executing the underlying query
Resync Refreshes the Recordset to the current database values
Save Saves the Recordset to a file
Supports Returns whether the object supports a particular function
Update Saves the changes to the current row to the database
UpdateBatch Saves the changes of the current batch to the database

Table D.22. Recordset Object Properties

PROPERTY Description
AbsolutePage Returns or sets the page of the current record
AbsolutePosition Returns or sets the current record position by ordinal
ActiveCommand Returns the command object that created the Recordset
ActiveConnection Returns the active connection used by the Recordset
BOF Returns whether the current record position is before the beginning of the Recordset
Bookmark Returns or sets a bookmark for the current record
CacheSize Returns or sets the number records that will be cached in local memory
CursorLocation Returns or sets where the cursor will be created
CursorType Returns or sets the type of cursor
DataMember Returns or sets the data member to retrieve from the object referenced by the datasource property
DataSource Returns or sets the object containing data the Recordset represents
EditMode Returns the editing status of the current record
EOF Returns if the current record position is past the end of the Recordset
Fields Returns the collection of Field object's in the Recordset
Filter Returns or sets the filter for data
LockType Returns or sets the locking strategy
MarshalOptions Returns or sets how the Recordset should be marshaled using DCOM
MaxRecords Returns or sets the maximum number of records to return
PageCount Returns the number of pages the Recordset contains
PageSize Returns or sets the size of the pages
Properties Returns the dynamic properties for the object
RecordCount Returns the number of records
Sort Returns or sets the sort criteria
Source Returns or sets the source of the data
State Returns the current state of the object
Status Returns the status with regards to batch updates
StayInSync Returns or sets whether the parent row should change when underlying child rows change in a hierarchical Recordset


Previous chapterNext chapterContents

© Copyright, Macmillan Computer Publishing. All rights reserved.