什么叫无效的描述符索引

type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception javax.servlet.ServletException: [Microsoft][ODBC SQL Server Driver]无效的描述符索引
org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:825)
org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:758)
org.apache.jsp.index1_jsp._jspService(index1_jsp.java:204)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
root cause java.sql.SQLException: [Microsoft][ODBC SQL Server Driver]无效的描述符索引
sun.jdbc.odbc.JdbcOdbc.createSQLException(JdbcOdbc.java:6106)
sun.jdbc.odbc.JdbcOdbc.standardError(JdbcOdbc.java:6263)
sun.jdbc.odbc.JdbcOdbc.SQLGetDataString(JdbcOdbc.java:3307)
sun.jdbc.odbc.JdbcOdbcResultSet.getDataString(JdbcOdbcResultSet.java:5492)
sun.jdbc.odbc.JdbcOdbcResultSet.getString(JdbcOdbcResultSet.java:342)
sun.jdbc.odbc.JdbcOdbcResultSet.getString(JdbcOdbcResultSet.java:399)
org.apache.jsp.index1_jsp._jspService(index1_jsp.java:148)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
note The full stack trace of the root cause is available in the Apache Tomcat/5.0.28 logs.