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<h1>ASP.NET - Database Connection</h1>
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<p class="intro">ADO.NET is also a part of the .NET Framework. ADO.NET is used to handle
data access.
With ADO.NET you can work
with databases.</p>
<hr />
<h2>Examples</h2>
<p><a target="_blank" href="showasp.asp@filename=demo_dbconn_repeater">Database connection - Bind to a Repeater control</a></p>
<p><a target="_blank" href="showasp.asp@filename=demo_dbconn_datalist">Database connection - Bind to a DataList control</a></p>
<hr />
<h2>What is ADO.NET?</h2>
<ul>
<li>ADO.NET is a part of the .NET Framework</li>
<li>ADO.NET consists of a set of classes used to handle data access</li>
<li>ADO.NET is entirely based on
XML</li>
<li>ADO.NET has, unlike ADO, no Recordset object</li>
</ul>
<hr />
<h2>Create a Database Connection</h2>
<p>We are going to use the Northwind database in our examples.</p>
<p>First, import the "System.Data.OleDb"
namespace. We need this namespace to work with Microsoft Access and other OLE DB
database providers. We will create the connection to the database in the Page_Load subroutine.
We create a dbconn variable as a new OleDbConnection class with a connection
string which identifies the OLE DB provider and
the location of the database. Then we open the database connection:</p>
<table class="ex" border="1" width="100%">
<tr><td>
<pre><%@ Import Namespace="System.Data.OleDb" %></pre>
<pre><script runat="server">
sub Page_Load
dim dbconn
dbconn=New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;
data source=" & server.mappath("northwind.mdb"))
dbconn.Open()
end sub
</script></pre>
</td></tr>
</table>
<p> <b>Note:</b> The connection string must be a continuous string without a
line break!</p>
<hr />
<h2>Create a Database Command</h2>
<p>To specify the records to retrieve from the database, we will create a dbcomm
variable as a new OleDbCommand class. The OleDbCommand class is for issuing SQL
queries against database tables:</p>
<table class="ex" border="1" width="100%">
<tr><td>
<pre><%@ Import Namespace="System.Data.OleDb" %></pre>
<pre><script runat="server">
sub Page_Load
dim dbconn,sql,dbcomm
dbconn=New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;
data source=" & server.mappath("northwind.mdb"))
dbconn.Open()
sql="SELECT * FROM customers"
dbcomm=New OleDbCommand(sql,dbconn)
end sub
</script></pre>
</td></tr>
</table>
<br />
<hr />
<h2>Create a DataReader</h2>
<p>The OleDbDataReader class is used to read a stream of records from a data
source. A DataReader is created by calling the ExecuteReader method of the
OleDbCommand object:</p>
<table class="ex" border="1" width="100%">
<tr><td>
<pre><%@ Import Namespace="System.Data.OleDb" %></pre>
<pre><script runat="server">
sub Page_Load
dim dbconn,sql,dbcomm,dbread
dbconn=New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;
data source=" & server.mappath("northwind.mdb"))
dbconn.Open()
sql="SELECT * FROM customers"
dbcomm=New OleDbCommand(sql,dbconn)
dbread=dbcomm.ExecuteReader()
end sub
</script></pre>
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</table>
<br />
<hr />
<h2>Bind to a Repeater Control</h2>
<p>Then we bind the DataReader to
a Repeater control:</p>
<table class="ex" border="1" width="100%">
<tr><td>
<pre><%@ Import Namespace="System.Data.OleDb" %></pre>
<pre><script runat="server">
sub Page_Load
dim dbconn,sql,dbcomm,dbread
dbconn=New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;
data source=" & server.mappath("northwind.mdb"))
dbconn.Open()
sql="SELECT * FROM customers"
dbcomm=New OleDbCommand(sql,dbconn)
dbread=dbcomm.ExecuteReader()
customers.DataSource=dbread
customers.DataBind()
dbread.Close()
dbconn.Close()
end sub
</script></pre>
<pre><html>
<body></pre>
<pre><form runat="server">
<asp:Repeater id="customers" runat="server"></pre>
<pre><HeaderTemplate>
<table border="1" width="100%">
<tr>
<th>Companyname</th>
<th>Contactname</th>
<th>Address</th>
<th>City</th>
</tr>
</HeaderTemplate></pre>
<pre><ItemTemplate>
<tr>
<td><%#Container.DataItem("companyname")%></td>
<td><%#Container.DataItem("contactname")%></td>
<td><%#Container.DataItem("address")%></td>
<td><%#Container.DataItem("city")%></td>
</tr>
</ItemTemplate></pre>
<pre><FooterTemplate>
</table>
</FooterTemplate></pre>
<pre></asp:Repeater>
</form></pre>
<pre></body>
</html></pre>
</td></tr>
</table>
<br />
<hr />
<h2>Close the Database Connection</h2>
<p>Always close both the DataReader and database connection after access to the database is no longer required:</p>
<table class="ex" border="1" width="100%">
<tr><td>
<pre>dbread.Close()
dbconn.Close()</pre>
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