从servlet执行oracle查询的错误结果

Question

我正在使用以下代码执行查询。 我想通过使用lpad命令和串联将结果显示为“ B010025”。（25和B01作为输入值）。 但它仅显示B0125。 当我从SQL * Plus执行此操作时，它将显示正确的结果。 但是在servlet中却没有。 我听不懂 谁能帮助我获得预期的结果。

public class PickOfferNo extends HttpServlet {


protected void processRequest(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    response.setContentType("text/html;charset=UTF-8");
    PrintWriter out = response.getWriter();
    try {
         //TODO output your page here
        out.println("<html>");
        out.println("<head>");
        out.println("<title>Servlet PickOfferNo</title>");  
        out.println("</head>");
        out.println("<body>");
        out.println("<h1>Servlet PickOfferNo at " + request.getContextPath () + "</h1>");
        out.println("</body>");
        out.println("</html>");

    } finally {            
        out.close();
    }
}

// <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">

@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    //processRequest(request, response);

    response.setContentType("text/html;charset=UTF-8");
    PrintWriter out = response.getWriter();
    try
    {
        out.println("<html>");
        out.println("<head>");
        out.println("<title>Servlet PickOfferNo</title>");
        out.println("</head>");
        out.println("<body>");
        out.println("<h1>Servlet PickOfferNo at " + request.getContextPath () + "</h1>");
        doPost(request,response);
        out.println("</body>");
        out.println("</html>");
    }
    finally
    {
       out.close(); 
    }
}


@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    //processRequest(request, response);
    String ofrn=null;
    //String cd=null;
    //String no=null;
    String cd="B01";
    String no="25";
    JSONObject obj = new JSONObject();
    //cd=request.getParameter("sec_code");
    PrintWriter out=response.getWriter();
    try
    {
        Class.forName("oracle.jdbc.driver.OracleDriver");
        java.sql.Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@192.168.1.200:1521:pdsm", "test", "test");
             Statement stmt=conn.createStatement();
                 conn.setAutoCommit(true);
                 //ResultSet rs=stmt.executeQuery("select to_char(nvl(max(substr(offerno,4,4)),0)+1) into '"+no+"' from offer1 where div_sec='"+cd+"'");
                 ResultSet rs1=stmt.executeQuery("select lpad(ltrim(rtrim('"+no+"')),4,'0') from dual");
                 //while(rs1.next())
                 ofrn=cd+no;

                 //obj.put("offrn", ofrn);
                 out.println(ofrn);
    }
    catch(Exception e)
    {
        out.println(e.getMessage());
    }
}


@Override
public String getServletInfo() {
    return "Short description";
}// </editor-fold>
}

提前致谢

Answer 1

只要：

String cd="B01";
String no="25";

和：

ofrn=cd+no;

对输出结果有贡献：

out.println(ofrn);

因此，没有任何意外发生！

Answer 2

这是因为您尚未选择数据库返回的值。 执行中

"select lpad(ltrim(rtrim('"+no+"')),4,'0') from dual"

不会更改“ no”或“ cd”的值。

您应该获取结果集并对其进行处理，以访问结果集返回的第一行中的第一列。

以下代码应完成分配。 （未经测试。）

ResultSet rs1=stmt.executeQuery("select lpad(ltrim(rtrim('"+no+"')),4,'0') from dual");
if(rs1.next()){
no = rs1.getString(1);
}

Answer 3

您从未为cd和no赋值。

    ResultSet rs1=stmt.executeQuery("select lpad(ltrim(rtrim('"+no+"')),4,'0') from dual");
    //while(rs1.next())
    ofrn=cd+no;

    //obj.put("offrn", ofrn);
    out.println(ofrn);

从servlet执行oracle查询的错误结果

问题描述

3 个解决方案

解决方案1
1 2013-01-18 11:59:05

解决方案2
1 已采纳 2013-01-18 11:59:10

解决方案3
0 2013-01-18 11:56:39

从servlet执行oracle查询的错误结果

问题描述

3 个解决方案

解决方案1 1 2013-01-18 11:59:05

解决方案2 1 已采纳 2013-01-18 11:59:10

解决方案3 0 2013-01-18 11:56:39

解决方案1
1 2013-01-18 11:59:05

解决方案2
1 已采纳 2013-01-18 11:59:10

解决方案3
0 2013-01-18 11:56:39