thks for the info. I was able to do mailmerge using vb.net. i have found two
ways.both are working
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Imports Microsoft.Office.Interop

'method 1
Private Sub MailMerge_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button5.Click

       'open the word template using openfiledialog box
       OpenFileDialog1.InitialDirectory =
My.Computer.FileSystem.SpecialDirectories.Desktop & "\word Template"
       'By default .dot file
       OpenFileDialog1.Filter = "Template Files (*.dot)|*.dot|All Files
(*.*)|*.*"
       OpenFileDialog1.Title = "Open a Word Template file---> *.dot"

       'if file is selected
       If Me.OpenFileDialog1.ShowDialog =
System.Windows.Forms.DialogResult.OK Then

           Dim m_FileName As String
           'open word application
           Dim mWord As New Word.ApplicationClass
           'open word document
           Dim mWordDoc As New Word.Document
           'create mailmerge fields
           Dim mMergeField As Word.MailMergeField
           'assign the path value
           m_FileName = OpenFileDialog1.FileName

           'Dim wordTemplateName As Object
           Dim wordTemplateName As String
           'assign word template name
           wordTemplateName = m_FileName

           ' Dim destinationFileName As Object
           Dim destinationFileName As String
           'word is not visible
           mWord.Visible = False

           Dim i As Integer = 1

           'create sql connection
           Dim objConn As SqlClient.SqlConnection
           Dim ds As New DataSet
           Dim m_strConnection As String = "Data Source=ServerName;initial
catalog=databasename;Integrated security=true;"

           objConn = New SqlClient.SqlConnection
           objConn.ConnectionString = m_strConnection
           objConn.Open()

           'to pass query
           Dim objCommand As SqlClient.SqlCommand
           Dim strSQL As String
           'read the data
           Dim myreader As SqlClient.SqlDataReader

    'select onlt top 10 rows for testing purpose
           strSQL = "select top 10
FirstName,LastName,Dear,Addr1,City,State,Zip,Country,SalesAssociate from
contactpipe"
           objCommand = New SqlClient.SqlCommand(strSQL, objConn)
           myreader =
objCommand.ExecuteReader(CommandBehavior.CloseConnection)

           Dim num As Integer = 0
           
           '-------------------------------->
           'read row by row
           While myreader.Read()
               'counter
               num = num + 1
               'create a new document
               mWordDoc = mWord.Documents.Add(wordTemplateName, , , )

               'loop thru word merge fields and assign values
               For Each mMergeField In mWordDoc.MailMerge.Fields

                   mMergeField.Select()
                   'get the merge field name with  «name» ; »this sign
copied and pasted from word
                   ''MsgBox((CStr(CInt(AscW("«"c)))))--->187,171
                   If mWord.Selection.Range.Text = "«" & "FirstName" & "»"
Then
                       
mWord.Selection.TypeText(myreader("FirstName").ToString())
                   ElseIf mWord.Selection.Range.Text = "«" & "LastName" &
"»" Then
                       
mWord.Selection.TypeText(myreader("LastName").ToString())
                   ElseIf mWord.Selection.Range.Text = "«" & "Street" & "»"
Then
                       mWord.Selection.TypeText(myreader("Addr1").ToString())
                   ElseIf mWord.Selection.Range.Text = "«" & "City" & "»"
Then
                       mWord.Selection.TypeText(myreader("City").ToString())
                   ElseIf mWord.Selection.Range.Text = "«" & "State" & "»"
Then
                       mWord.Selection.TypeText(myreader("State").ToString())
                   ElseIf mWord.Selection.Range.Text = "«" & "PostalCode" &
"»" Then
                       mWord.Selection.TypeText(myreader("Zip").ToString())
                   ElseIf mWord.Selection.Range.Text = "«" & "Country" &
"»" Then
                       
mWord.Selection.TypeText(myreader("Country").ToString())
                   ElseIf mWord.Selection.Range.Text = "«" & "Date" & "»"
Then
                       mWord.Selection.TypeText(Today.ToShortDateString)
                   ElseIf mWord.Selection.Range.Text = "«" & "Dear" & "»"
Then
                       mWord.Selection.TypeText(myreader("Dear").ToString())
                   ElseIf mWord.Selection.Range.Text = "«" & "Sender" & "»"
Then
                       
mWord.Selection.TypeText(myreader("SalesAssociate").ToString())
                   Else
                       mWord.Selection.TypeText("No_data_found")
                   End If

               Next mMergeField

               ''save the template as document ;todo check for same file
name before save the doc if found append some character
               ''to do:send to printer or email,dispaly the document
               destinationFileName = "C:\word Template\" &
myreader("FirstName").ToString() & num & ".doc"
               mWordDoc.SaveAs(destinationFileName)

           End While

           '-------------------------------->
           'clear the objects from memory
           myreader.Close()
           objConn.Close()
           myreader = Nothing
           objCommand = Nothing

           mWord.Quit()
           mWord = Nothing
           mWordDoc = Nothing
           mMergeField = Nothing
           
       End If
==================================================================
'method 2
Private Sub MailMerge_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button6.Click

       'initialize word
       oApp = CreateObject("Word.Application")
       'create word document
       Dim oMainDoc As Word.Document
       
       'Start a new main document for  mail merge ;assign the word template
path
       oMainDoc = oApp.Documents.Add("C:\word Template\MyTemplate.dot")

       With oMainDoc.MailMerge
           'mail document type
           .MainDocumentType = WdMailMergeMainDocType.wdFormLetters
           'sql statement
           Dim strSQL As String = "select top 10
FirstName,LastName,Dear,Addr1,City,State,Zip,Country,SalesAssociate from
contactpipe"
           'pass the DSN info;"DSN=Connect_To_DB"-->already created using
ODBC
           .OpenDataSource(Name:="", Connection:="DSN=Connect_To_DB",
SQLStatement:=strSQL)
       End With

       'Perform the mail merge to a new document.
       With oMainDoc
           .MailMerge.Destination =
WdMailMergeDestination.wdSendToNewDocument
           .MailMerge.Execute(Pause:=False)
       End With

       'close the template
       oMainDoc.Saved = True

       oMainDoc.Close(False)
       oApp.Visible = True
       MessageBox.Show("Mail Merge Complete: " & oApp.ActiveDocument.Name,
"Mail Merge", MessageBoxButtons.OK, MessageBoxIcon.Information,
MessageBoxDefaultButton.Button3, MessageBoxOptions.DefaultDesktopOnly)

   End Sub
===============
Questions:
1)in method 1 ,i am saving each merged record as a file
a)How to show all the merged records in one document with new pages or read
the saved files and put them in one word document. Each file info should be
in a new page?
2)in method 2,How to replace DSN info wth slq server connection string
like "Data Source=servername;initial catalog=dbname;Integrated security=true;"
or the provider name. I am using sql server 2000
3)if I give the user an option to create a new template;
a)how to restrict the merge field values:what i mean is user only able to
see the mergefields that i created(in the dropdown box)

thanks in advance