ASP.NET database connection
I have the correct entries in the web.config file in my ASP.NET project. How do I make sure that the connection has been established successfully? I want to pull an image form my database and then display it on my aspx page. Some things to note: I am using Visual Studio 2010, SQL server 2008, .NET 4.0
web.config file
<databases>
<add key=&q开发者_JAVA百科uot;MyConnection" name="MyName" value="server=servername\SQL2008;uid=myuid;pwd=mypwd;database=databaseName;"/>
<add key="DataAccessClass" value="DataAccessSql"/>
</databases>
I do not have any app.config file in my project yet. Surprisingly there is not section in my web.config. Do I need to add one explicitly?
Web.config file is just a store for configuration settings. In order to establish a connection to the database you need to write some code.
ASP.NET - Database Connection
Creating Connections to SQL Server
The connection parameters entered in the web.config file are just parameters. No actual connections are made. In fact, multiple connection parameters can be made in the web.config and the actual connection can be made at runtime.
To actually make a connection happen, you need to define
For instance, here the SQLDataSource is set to connect to ConnectionStrings.MyNorthwind
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>ASP.NET Example</title>
</head>
<body>
<form id="form1" runat="server">
<asp:SqlDataSource
id="SqlDataSource1"
runat="server"
DataSourceMode="DataReader"
ConnectionString="<%$ ConnectionStrings:MyNorthwind%>"
SelectCommand="SELECT LastName FROM Employees">
</asp:SqlDataSource>
<asp:ListBox
id="ListBox1"
runat="server"
DataTextField="LastName"
DataSourceID="SqlDataSource1">
</asp:ListBox>
</form>
</body>
</html>
or in this second example, where they explicitely create an SqlConnection. The connectionstring here would be taken from the web.config.
private static void ReadOrderData(string connectionString)
{
string queryString =
"SELECT OrderID, CustomerID FROM dbo.Orders;";
using (SqlConnection connection = new SqlConnection(
connectionString))
{
SqlCommand command = new SqlCommand(
queryString, connection);
connection.Open();
SqlDataReader reader = command.ExecuteReader();
try
{
while (reader.Read())
{
Console.WriteLine(String.Format("{0}, {1}",
reader[0], reader[1]));
}
}
finally
{
// Always call Close when done reading.
reader.Close();
}
}
}
Here is an example of a connection string to be found in your web.config
<configuration>
<connectionStrings>
<add name="ApplicationServices"
connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|\aspnetdb.mdf;User Instance=true"
providerName="System.Data.SqlClient" />
</connectionStrings>
</configuration>
加载中,请稍侯......
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