Data binding is the act of connecting a control in the programming environment directly to a field i

1
Data Services Provided by VB

• Data binding is the act of connecting a control
  in the programming environment directly to a
  field in a row in a Recordset so that users can
  directly view and edit the data by changing the
  control contents.
• ADO (ActiveX Data Objects) is the newest standard
  for data access from MS programming environments.

2
Objects in the ADO Object Model

• Connection object specifies information about
  the physical connection with a data source.
• Command object store actions performed on the
  data, such as data modification and retrieval.
• Recordset object provides a rich selection of
  properties, events, and methods to expose data in
  a field-row format.

3
Setting Up the ADO Data Control

• Add the MS ADO DataControl 6.0 from the Project,
  Components menu dialog box if the ADO Data
  Control icon doesnt appear in the toolbox.
• Place an instance of the ADO Data Control on the
  form.
• Specify the ConnectionString property for the
  ADO Data Control.
• Specify the RecordSource property for the ADO
  Data Control.

4
Binding VB Controls to the ADO Data Controls
Recordset

• Place a VB control on the form.
• Click on down arrow on the DataSource property
  for the control to select the ADB Data Control.
• Set the controls DataField property by
  clicking the down arrow on the DataField
  property to pick a field from the ADOs recordset.

5
Set up a Connection in Code

• Set a reference to the latest ADO Library from
  the Project, References menu dialog box.
• Declare an object variable whose type is
  ADODB.Connection.
• Set the Connection objects ConnectString
  property.
• Call the Connection objects Open method.
• Dim cnIntro As ADODB.Connection
• Set cnIntro New ADODB.Connection '
  Connection object
• cnIntro.ConnectString Provider
  Microsoft.Jet.OLEDB.3.51
• cnIntro.open
• Private sConnect As String
• sConnect DSN oracle UID ltyour idgt PWD
  ltyour pwdgt
• mobjDBConn.Open mDsnConnect

6
Connection Object Events

• WillConnect monitor information about the
  pending connection thats about to be opened to a
  provider.
• WillExecute examine and change the settings for
  the action that will be executed on the provider.
• BeginTransComplete, CommitTransComplete, and
  RollbackTransComplete deal with database
  transactions.
• Disconnect perform post-connection cleanup.

7
Set up a Recordset in Code

• Make sure you have a valid Connection or Command
  object.
• Declare an object variable whose type is
  ADODB.Recordset.
• Set the Recordset objects Source property.
• Call the Recordset objects Open method.
• Dim rsIntro As ADODB.Recordset
• Set rsIntro New ADODB.Recordset
• rsIntro.Source SELECT FROM lttable namegt
• Set rsIntro.ActiveConnection cnIntro
• rsIntro.Open

8
Manipulate a Recordsets Data with Its Methods

• Every open Recordset must be associated with a
  data cursor.
• The five most common methods that enable you to
  move the cursor Move, MoveFirst, MoveLast,
  MoveNext, MovePrevious
• Two most common methods that check on the cursor
  BOF, EOF
• Locate records the Find method takes up to four
  arguments
• Criterion (required) a string as the SQL where
  clause
• SkipRows a number representing the offset of
  the starting position
• searchDirection a flag indicating the direction
  in which to search from the starting point
• Start a double-type value that gives the
  Bookmark of the record from which the search will
  begin

9
Manipulate a Recordsets Data with Its Methods

• Every open Recordset must be associated with a
  data cursor. The five most common methods that
  enable you to move the cursor Move, MoveFirst,
  MoveLast, MoveNext, MovePrevious
• Refer to Recordset field contents
• rsIntro.Field(2).value
• rsIntro.Fields(ltfieldnamegt).value
• rsIntro(ltfieldnamegt).value
• reIntro!ltfieldname
• Update a record assign values to fields first,
  then call rsIntro.Update
• Add a record rsIntro.AddNew then update a
  record
• Delete a record rsIntro.Delete

10
Initialize Command Objects in Code

• Make sure your have a valid Connection.
• Declare an object variable whose type is
  ADODB.Command.
• Set the Command objects CommandType property.
• Set the Command objects CommandText property.
• Call the Connection objects Execute method.
• Set the Connection objects ActiveConnection
  property to point to a valid existing Connection
  object.

11
Sample Code for Initializing Command Objects
Dim comIntro As ADODB.Command Set comIntro New
ADODB.Connection With comIntro Set
.ActiveConnection cnIntro .CommandType
adCmdText .CommandText sqlStr .Prepared
True Set rsIntro .Execute(sqlStr) End With