Question

rs=stmt.executeQuery(sql)出错是怎么回事

HTTP Status 500 -

--------------------------------------------------------------------------------

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException: Exception in JSP: /good_add_deal.jsp:37

34: String sql="";
35: sql="select*from goodinfo where gid='"+gid+"'";
36:
37: ResultSet rs=stmt.executeQuery(sql);
38:
39: if(!rs.next()){
40: out.println("<script language='javascript'>alert('该商品信息已经添加！');history.back(-1);</script>");

Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:491)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:413)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:308)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:259)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)

root cause

java.lang.StringIndexOutOfBoundsException: String index out of range: -1
java.lang.String.substring(String.java:1937)
sun.jdbc.odbc.JdbcOdbcResultSet.reWordAsCountQuery(JdbcOdbcResultSet.java:6558)
sun.jdbc.odbc.JdbcOdbcResultSet.calculateRowCount(JdbcOdbcResultSet.java:6351)
sun.jdbc.odbc.JdbcOdbcResultSet.initialize(JdbcOdbcResultSet.java:155)
sun.jdbc.odbc.JdbcOdbcStatement.getResultSet(JdbcOdbcStatement.java:424)
sun.jdbc.odbc.JdbcOdbcStatement.executeQuery(JdbcOdbcStatement.java:254)
org.apache.jsp.good_005fadd_005fdeal_jsp._jspService(good_005fadd_005fdeal_jsp.java:86)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:371)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:308)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:259)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)

Answer 1

你的sql语句别怎么写，String sql=String.format("select*from goodinfo where gid='%d'",gid);
我这里假设你的商品编号是整形的，所以用的占位符是%d，如果你是String类型，那占位符就用%s，用这样写万无一失，你上面的那种写法我以前也是这样写的，有时候有用，有时候没有，干脆改成这样吧。

Answer 2

gid是字符串还是整型,整型的话不需要单引号的

Answer 3

先确保sql语句没问题