Difference between revisions of "DD Class9"

Revision as of 02:27, 9 November 2009

DataReader

• DataReader http://iam.colum.edu/dd/classsource/ado/dataReader.aspx source

1 Connection Object <csharp> //Connection string comes from web config SqlConnection objConnection = new SqlConnection(ConfigurationManager.ConnectionStrings["cheeseConnectionString"].ConnectionString); </csharp>

web.config connection strings

<xml> <configuration>

              <connectionStrings>

<add name="cheeseConnectionString" connectionString="Data Source=iamdb;Initial Catalog=cheese;User ID=student;Password=Student" providerName="System.Data.SqlClient"/> </connectionStrings> </xml>

2 Command Object <csharp>string strSQL = "SELECT CheeseName,CheeseDescription FROM cheese";

   string strResultsHolder = "";
   
   SqlCommand objCommand = new SqlCommand(strSQL, objConnection);

</csharp>

3 Reader and Reading <csharp> SqlDataReader objDataReader = null; //Reader to read through the result

   try
   {
       objConnection.Open();                                       //Open Connection
       objDataReader = objCommand.ExecuteReader();

       while (objDataReader.Read() == true)
       {
           strResultsHolder += String.Format("{0}:{1}

",
               objDataReader["CheeseName"], objDataReader["CheeseDescription"]);
       }
   }
   catch (Exception e)
   {
       lblErr.Text = "Connection failed to open successfully.
";
       lblErr.Text += e.ToString();
   }
   finally
   {
       objDataReader.Close();      //Close Reader
       objConnection.Close();      //Close Connection

   }
   //Write results
   divListCheese.InnerHtml = strResultsHolder;

}

</csharp>

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