菜鸟请教JSP+SQL留言板的问题，3个错误~搞不明白啊~~谢谢啦
org.apache.jasper.JasperException:   Unable   to   compile   class   for   JSP

An   error   occurred   at   line:   15   in   the   jsp   file:   /jspmo/index.jsp
Generated   servlet   error:
C:\Program   Files\Apache   Software   Foundation\Tomcat   5.0\work\Catalina\localhost\news\org\apache\jsp\jspmo\index_jsp.java:93:   cannot   resolve   symbol
symbol     :   variable   tab  
location:   class   org.apache.jsp.jspmo.index_jsp
String   sql= "select   *   from   "+tab+ "   order   by   id   desc ";  
                                                                                        ^


An   error   occurred   at   line:   15   in   the   jsp   file:   /jspmo/index.jsp
Generated   servlet   error:
C:\Program   Files\Apache   Software   Foundation\Tomcat   5.0\work\Catalina\localhost\news\org\apache\jsp\jspmo\index_jsp.java:94:   cannot   resolve   symbol
symbol     :   variable   st  
location:   class   org.apache.jsp.jspmo.index_jsp
java.sql.ResultSet   rs   =   st.executeQuery(sql);
                                                                                ^


An   error   occurred   at   line:   413   in   the   jsp   file:   /jspmo/index.jsp
Generated   servlet   error:
C:\Program   Files\Apache   Software   Foundation\Tomcat   5.0\work\Catalina\localhost\news\org\apache\jsp\jspmo\index_jsp.java:585:   cannot   resolve   symbol
symbol     :   variable   st  
location:   class   org.apache.jsp.jspmo.index_jsp
st.close();  
^
3   errors

index.jsp(部分)
<%
int   i=0,x=0;//计数器
int   showrow=4;//每页显示条数
int   pages=0;//当前页数
int   start;   //本页开始条数
String   sql= "select   *   from   "+tab+ "   order   by   id   desc ";  
java.sql.ResultSet   rs   =   st.executeQuery(sql);
String   strp=(String)request.getParameter( "pages ");
String   pass=null;pass=(String)session.getAttribute( "pass ");

救命啊，如果要index原件联系我ＱＱ１６０３８５７９谢谢达人了，还有很多关于ＪＳＰ方面问题请教～

------解决方案--------------------
对于要读写数据库的语句要放在try...catch(Excetpion e){}里.
------解决方案--------------------
tab是否声明并初始化，st 是否定义？executeQuery的SQLException捕获了吗？
我的异常网推荐解决方案：org.apache.jasper.JasperException: Unable to compile class,http://www.aiyiweb.com/j2ee/2308.