In your codebehind, declare your additional connection string.

Imports System.Data.SqlClient

Protected dbCon As New SqlConnection(ConfigurationManager.AppSettings("project_connection"))

Then just use it as you would for any other dr object.

Sub GenUserNameString()
 'for demonstration purposes
 'generates a string of all usernames
 'separated by a comma

 Dim UserNameList As String

 dbCon.Open()

 Dim Sql As String
 Dim cmd As New SqlCommand
 Dim dr As SqlDataReader

 Sql = ""
 Sql += "SELECT "
 Sql += "'username' = username "
 Sql += "FROM dbo.users "

 'Execute SQL Command
 cmd.CommandType = CommandType.Text
 cmd.CommandText = Sql
 cmd.Connection = dbCon

 dr = cmd.ExecuteReader()

 While dr.Read()
  UserNameList += "'" & dr(0).ToString() & "',"
 End While
 
 dr.Close()
 dbCon.Close()
 
 UserNameList = Left(UserNameList, Len(UserNameList) - 1)
 Response.Write("UserNameList: " & UserNameList & "<br>")
End Sub