Question

我有一个如下的jsp。

<%@page contentType="text/html" pageEncoding="UTF-8"%>
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
    <html>
        <head>
            <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
            <title>JSP Page</title>
        </head>
        <body>
            <form name="a" action="abc.jsp" method="post">
            <input type="abc" id="abc" name="abc">
            <input type="def" id="def" name="def"></form>
        </body>
    </html>

and the jsp that it is redirected is as below 

        <%@include file="DBCon.jsp" %>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
    </head>
    <body>
        <%try
            {
           int s;
        String a=request.getParameter("a");
        String b=request.getParameter("b");
        String c=request.getParameter("Ship_ID");
        ps=con.prepareStatement("select TSI_QUERY,TSI_R,TSI_C,SI_QUERY,SI_R, SI_C from topical");
        rs=ps.executeQuery();
        if(rs.next()){
        if(rs.getString("TSI_Query")==null && rs.getString("SI_Query")!=null)
        {
            String p="update topical set SI_Query='"+a+"', SI_R='x',SI_C='y' where Job_ID='"+c+"'";
            System.out.print(p);
            /*ps1=con.prepareStatement("update topical set TSI_Query=?, TSI_R=?,TSI_C=?");
            ps1.setString(1, a);
            ps1.setString(2, "x");
            ps1.setString(3, "y");
            s=ps1.executeUpdate();
            if(s!=0){
                String redirectURL= "a.jsp";
                response.sendRedirect(redirectURL);
            }*/
        }
              else if(rs.getString("SI_Query")==null && rs.getString("TSI_Query")!=null)
        {
            String p="update topical set SI_Query='"+b+"', SI_R='x',SI_C='y'where Job_ID='"+c+"'";
            System.out.print(p);

            /*ps1=con.prepareStatement("update topical set SI_Query=?, SI_R=?,SI_C=?");
            ps1.setString(1, b);
            ps1.setString(2, "x");
            ps1.setString(3, "y");
            s=ps1.executeUpdate();
            if(s!=0){
            String redirectURL= "a.jsp";
            response.sendRedirect(redirectURL);}*/
        }
               else if(rs.getString("SI_Query")==null && rs.getString("TSI_Query")==null){
                   if(a==null && b!=null)
                                             {
                 String p="update topical set TSI_Query='"+a+"', TSI_R='x',TSI_C='y'where Job_ID='"+c+"'";
            /* ps1=con.prepareStatement("update topical set TSI_Query=?, TSI_R=?,TSI_C=?");
            ps1.setString(1, a);
            ps1.setString(2, "x");
            ps1.setString(3, "y");
            s=ps1.executeUpdate();
             if(s!=0){
                String redirectURL= "a.jsp";
                response.sendRedirect(redirectURL);
                               }
              */     }
                 else if(b==null && a!=null){
            String p="update topical set SI_Query='"+b+"', SI_R='x',SI_C='y'where Job_ID='"+c+"'";
            System.out.print(p);
                     /*
            ps1=con.prepareStatement("update topical set SI_Query=?, SI_R=?,SI_C=?");
            ps1.setString(1, b);
            ps1.setString(2, "x");
            ps1.setString(3, "y");
            s=ps1.executeUpdate();
            if(s!=0){
                String redirectURL= "a.jsp";
                response.sendRedirect(redirectURL);
                               }*/
                 }
               }
               }

        }
        catch(Exception e)
        {
        out.println(e);
        }
        %>
    </body>
</html>

这里我想更新我的数据库表，收到非空值，另一列不应该更新为null，因为此列可能会在另一次更新。但是，它显示的是空白页面，而不是任何查询字符串，请让我知道如何显示该查询字符串。

由于

Answer 1

如果我尝试理解您的代码，您似乎有三种情况

案例1

TSI_Query == null && SI_Query != null
//print something

案例2

SI_Query ==null && TSI_Query != null
//print something

案例3

SI_Query ==null && TSI_Query == null
  // check values of a and b, and print only if b==null && a!=null

所以你有效， NOT 遵循所有可能的路径！难怪你没有任何输出。请注意，你也可能是其他问题。

基于jsp输入更新数据库

1 个答案: