<%@Page Language="VB"%>

<%@Import Namespace="System.Data" %>
<%@Import Namespace="System.Data.OleDb" %>

<%@ Register TagPrefix="wrox" TagName="connect" Src="..\global\connect-strings.ascx" %>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html><head>
<title>The DataSet Object with Multiple Tables</title>
<!-- #include file="..\global\style.inc" -->
</head>
<body bgcolor="#ffffff">
<span class="heading">The DataSet Object with Multiple Tables</span><hr />
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<%'-- insert connection string script --%>
<wrox:connect id="ctlConnectStrings" runat="server"/>

<div>Connection string: <b><span id="outConnect" runat="server"></span></b></div>
<div>Books SELECT command: <b><span id="outSelectBooks" runat="server"></span></b></div>
<div>Authors SELECT command: <b><span id="outSelectAuthors" runat="server"></span></b></div>
<div>Prices SELECT command: <b><span id="outSelectPrices" runat="server"></span></b></div>
<div id="outError" runat="server">&nbsp;</div>

<b>DataSet.Tables Collection</b>
<asp:datagrid id="dgrTables" runat="server" /><br />
<b>DataSet.Relations Collection</b>
<asp:datagrid id="dgrRelations" runat="server" /><br />
<b>Contents of DataSet.Tables("Books")</b>
<asp:datagrid id="dgrBooksData" runat="server" /><br />
<b>Contents of DataSet.Tables("Authors")</b>
<asp:datagrid id="dgrAuthorsData" runat="server" /><br />
<b>Contents of DataSet.Tables("Prices")</b>
<asp:datagrid id="dgrPricesData" runat="server" />

<script language="vb" runat="server">

Sub Page_Load()

   'get connection string from ..\global\connect-strings.ascx user control
   Dim strConnect As String
   strConnect = ctlConnectStrings.JetConnectionString
   outConnect.innerText = strConnect 'and display it

   'specify the SELECT statement to extract the BookList data
   Dim strSelectBooks As String
   strSelectBooks = "SELECT * FROM BookList WHERE ISBN LIKE '18610033%'"
   outSelectBooks.innerText = strSelectBooks   'and display it

   'specify the SELECT statement to extract the BookAuthor data
   Dim strSelectAuthors As String
   strSelectAuthors = "SELECT * FROM BookAuthors WHERE ISBN LIKE '18610033%'"
   outSelectAuthors.innerText = strSelectAuthors   'and display it

   'specify the SELECT statement to extract the BookPrices data
   Dim strSelectPrices As String
   strSelectPrices = "SELECT * FROM BookPrices WHERE ISBN LIKE '18610033%'"
   outSelectPrices.innerText = strSelectAuthors   'and display it

   'declare a variable to hold a DataSet object
   'note that we have to create it outside the Try..Catch block
   'as this is a separate block and so is a different scope
   Dim objDataSet As New DataSet()

   Try

      'create a new Connection object using the connection string
      Dim objConnect As New OleDbConnection(strConnect)

      'create a new Command object
      Dim objCommand As New OleDbCommand()

      'set the properties
      objCommand.Connection = objConnect
      objCommand.CommandType = CommandType.Text
      objCommand.CommandText = strSelectBooks

      'create a new DataAdapter object
      Dim objDataAdapter As New OleDbDataAdapter()
      'and assign the Command object to it
      objDataAdapter.SelectCommand = objCommand

      'get the data from the "BookList" table in the database and
      'put it into a table named "Books" in the DataSet object
      objDataAdapter.Fill(objDataSet, "Books")

      'change the SELECT statement in the Command object
      objCommand.CommandText = strSelectAuthors
      'then get data from "BookAuthors" table into the DataSet
      objDataAdapter.Fill(objDataSet, "Authors")

      'and do the same again to get the "BookPrices" data
      objCommand.CommandText = strSelectPrices
      objDataAdapter.Fill(objDataSet, "Prices")

   Catch objError As Exception

      'display error details
      outError.innerHTML = "<b>* Error while accesing data</b>.<br />" _
          & objError.Message & "<br />" & objError.Source
      Exit Sub  ' and stop execution

   End Try

   'declare a variable to hold a DataRelation object
   Dim objRelation As DataRelation

   'create a Relation object to link Books and Authors
   objRelation = New DataRelation("BookAuthors", _
                     objDataSet.Tables("Books").Columns("ISBN"), _
                     objDataSet.Tables("Authors").Columns("ISBN"))
   'and add it to the DataSet object's Relations collection
   objDataSet.Relations.Add(objRelation)

   'now do the same to link Books and Prices
   objRelation = New DataRelation("BookPrices", _
                     objDataSet.Tables("Books").Columns("ISBN"), _
                     objDataSet.Tables("Prices").Columns("ISBN"))
   objDataSet.Relations.Add(objRelation)

   'now we're ready to display the contents of the DataSet object
   'bind the collection of Tables to the first DataGrid on the page
   dgrTables.DataSource = objDataSet.Tables
   dgrTables.DataBind()

   'bind the collection of Relations to the second DataGrid on the page
   dgrRelations.DataSource = objDataSet.Relations
   dgrRelations.DataBind()

   'create a DataView object to use with the tables in the DataSet
   Dim objDataView As New DataView()

   'get the default view of the Books table into the DataView object
   objDataView = objDataSet.Tables("Books").DefaultView
   'and bind it to the third DataGrid on the page
   dgrBooksData.DataSource = objDataView
   dgrBooksData.DataBind()

   'then do the same for the Authors table
   objDataView = objDataSet.Tables("Authors").DefaultView
   dgrAuthorsData.DataSource = objDataView
   dgrAuthorsData.DataBind()

   'and finally do the same for the Prices table
   objDataView = objDataSet.Tables("Prices").DefaultView
   dgrPricesData.DataSource = objDataView
   dgrPricesData.DataBind()

End Sub
</script>


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</body>
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