25.12. Deleting Records in a Database

You can delete records by making use of the SQL Delete command. To execute a delete command with EnterpriseDB .NET Connector you need to do the following:

Creating and opening a database connection
Creating a database command that represents the delete statement to be executed
Execute the delete command using the ExecuteNonQuery() method of EDBCommand.

In order to delete the employee that we inserted in the above example we would do something like the following:

Example 25-7. Example - Deleting a Database Record

   
<% @ Page Language="C#" Debug="true"%>
<% @Import Namespace="EnterpriseDB.EDBClient" %>
<% @Import Namespace="System.Data" %>

<script language="C#" runat="server" >

private void Page_Load(object sender, System.EventArgs e)
{
	string strConnectionString = ConfigurationSettings.AppSettings
	["DB_CONN_STRING"];
	
	EDBConnection conn = new EDBConnection(strConnectionString);
			
	string strDeleteQuery  = "DELETE FROM emp WHERE empno = :ID";	
	
	try {
		conn.Open();
			
		EDBCommand deleteCommand = new EDBCommand(strDeleteQuery,conn);
			
		deleteCommand.Parameters.Add
		(new EDBParameter(":ID", EDBTypes.EDBDbType.Integer));
	
		deleteCommand.Parameters[0].Value = 1234;							
				
		deleteCommand.ExecuteNonQuery();
				
		Response.Write("Record Deleted");
				
	}
	
	catch(Exception exp) { 
	
		Response.Write(exp.ToString());
		
	}
	
	finally {
	
		conn.Close();
		
	}
}
		
</script>

Save the file as "deleteEmployee.aspx" and run it like the other examples. If no errors are generated then a "Record Deleted" message should be shown.

25.12.1. Deleting Records in a Database - Explanation

The delete command is stored in the variable strDeleteQuery. We are passing one parameter to the Delete command, which is the employee number which is specified with ":EmpNo". Then the command is executed with the ExecuteNonQuery() method as we are not returning any values.