SqlConnection sqlConnection1 = new SqlConnection("Data Source=" + SqlServer + ";Initial Catalog=DhcpDB;Persist Security Info=True;User ID=user");

        SqlCommand selCommand = new SqlCommand(strSQL, sqlConnection1);

        sqlConnection1.Open();

        sqlConnection1.Close();

static extern short SQLConnect (int connectionHandle, string serverName,

    Private Function SQLConnect(ByVal hDBc As IntPtr, ByVal servername As String, ByVal serverlen As Short, _

     RetCode = SQLConnect(hdbc, "Northwind",-3,null,-3,null,-3);