ASP.NET - Database Connection
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.
Examples
Database connection - Bind to a Repeater control
Database connection - Bind to a DataList control
What is ADO.NET?
- ADO.NET is a part of the .NET Framework
- ADO.NET consists of a set of classes used to handle data access
- ADO.NET is entirely based on
XML
- ADO.NET has, unlike ADO, no Recordset object
Create a Database Connection
We are going to use the Northwind database in our examples.
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:
<%@ Import Namespace="System.Data.OleDb" %>
<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>
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Note: The connection string must be a continuous string without a
line break!
Create a Database Command
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:
<%@ Import Namespace="System.Data.OleDb" %>
<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>
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Create a DataReader
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:
<%@ Import Namespace="System.Data.OleDb" %>
<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>
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Bind to a Repeater Control
Then we bind the DataReader to
a Repeater control:
<%@ Import Namespace="System.Data.OleDb" %>
<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>
<html>
<body>
<form runat="server">
<asp:Repeater id="customers" runat="server">
<HeaderTemplate>
<table border="1" width="100%">
<tr>
<th>Companyname</th>
<th>Contactname</th>
<th>Address</th>
<th>City</th>
</tr>
</HeaderTemplate>
<ItemTemplate>
<tr>
<td><%#Container.DataItem("companyname")%></td>
<td><%#Container.DataItem("contactname")%></td>
<td><%#Container.DataItem("address")%></td>
<td><%#Container.DataItem("city")%></td>
</tr>
</ItemTemplate>
<FooterTemplate>
</table>
</FooterTemplate>
</asp:Repeater>
</form>
</body>
</html>
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Close the Database Connection
Always close both the DataReader and database connection after access to the database is no longer required:
dbread.Close()
dbconn.Close()
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