大家发过来了帖子，我都试过了，还是有错误呀，怎么办呀！

以下是我写的一段代码，可是为什么执行的结果一直是：“无法连接JDBC驱动程序！"
请各位大哥帮看一下，谢谢！
import java.sql.*;
import java.awt.*;
public class Jdbcexa
    {
      public static void main(String args[])
        {
        String url="jdbc:microsoft:SqlServer://WWWW:1433;DatabaseName=booksys";
        Connection con=null;
        Statement sm=null;
        ResultSet rs=null;
    
      try
         {
             Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver").newInstance();
         }
     catch(Exception e)
         {
            System.out.println("无法连接JDBC驱动程序!");
            return;
         }
      try
         {
               con=DriverManager.getConnection(url,"sa","");
               sm=con.createStatement();
               rs=sm.executeQuery("select * from bookinfo where 现有数量=1");
               System.out.println("结果为:");
            while(rs.next())
               {
                   String au_id=rs.getString(2);
                   System.out.println("au_id="+au_id);
               }
           }
             catch(SQLException e)
                {}
             finally
               {
                      try
                             {
                                     rs.close();
                                     sm.close();
                                     con.close();
                             }
                      catch(SQLException e)
                            {}
                     }
                  }       
    }