Skip to main content

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

Try it Yourself - Examples

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>
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>

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>

Bind to a Repeater Control

Then we bind the DataReader to a Repeater control:

Example

<%@ 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>

Show example »

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()

Comments

Post a Comment

Popular posts from this blog

Tip/Trick: Fix Common SEO Problems Using the URL Rewrite Extension

Search engine optimization (SEO) is important for any publically facing web-site.  A large % of traffic to sites now comes directly from search engines, and improving your site’s search relevancy will lead to more users visiting your site from search engine queries.  This can directly or indirectly increase the money you make through your site. This blog post covers how you can use the free Microsoft  URL Rewrite Extension  to fix a bunch of common SEO problems that your site might have.  It takes less than 15 minutes (and no code changes) to apply 4 simple  URL Rewrite  rules to your site, and in doing so cause search engines to drive more visitors and traffic to your site.  The techniques below work equally well with both ASP.NET Web Forms and ASP.NET MVC based sites.  They also works with all versions of ASP.NET (and even work with non-ASP.NET content). [In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at:  twitter.com/scottg
Post a Comment
Read more

C# Generic class to parse value - "GenericConverter"

    public class GenericConverter     {         public static T Parse<T>(string sourceValue) where T : IConvertible         {             return (T)Convert.ChangeType(sourceValue, typeof(T));         }         public static T Parse<T>(string sourceValue, IFormatProvider provider) where T : IConvertible         {             return (T)Convert.ChangeType(sourceValue, typeof(T), provider);         }     }     public static class TConverter     {         public static T ChangeType<T>(object value)         {             return (T)ChangeType(typeof(T), value);         }         public static object ChangeType(Type t, object value)         {             TypeConverter tc = TypeDescriptor.GetConverter(t);             return tc.ConvertFrom(value);         }         public static void RegisterTypeConverter<T, TC>() where TC : TypeConverter         {             TypeDescriptor.AddAttributes(typeof(T), new TypeConverterAttribute(typeof(TC)));         }     } ----------------
Post a Comment
Read more

ASP.NET MVC - Set custom IIdentity or IPrincipal

Here's how I do it. I decided to use IPrincipal instead of IIdentity because it means I don't have to implement both IIdentity and IPrincipal. Create the interface interface ICustomPrincipal : IPrincipal { int UserId { get ; set ; } string FirstName { get ; set ; } string LastName { get ; set ; } } CustomPrincipal public class CustomPrincipal : ICustomPrincipal { public IIdentity Identity { get ; private set ; } public bool IsInRole ( string role ) { return false ; } public CustomPrincipal ( string email ) { this . Identity = new GenericIdentity ( email ); } public int UserId { get ; set ; } public string FirstName { get ; set ; } public string LastName { get ; set ; } } CustomPrincipalSerializeModel - for serializing custom information into userdata field in FormsAuthenticationTicket object. public class CustomPrincipalSerializeMode
8 comments
Read more