Javascript 如果jsp页面的表中已经存在记录，如何获取错误消息_Javascript_Java_Html_Sql_Jsp

Javascript 如果jsp页面的表中已经存在记录，如何获取错误消息

javascript java html sql jsp

Javascript 如果jsp页面的表中已经存在记录，如何获取错误消息,javascript,java,html,sql,jsp,Javascript,Java,Html,Sql,Jsp,我有一个index.jsp页面，从中我将名称和id插入到oracle表中。我能够成功插入，但当用户再次输入相同的员工id时，index.jsp页面将重定向到tomcat错误页面 HTTP Status 500 javax.servlet.ServletException:java.sql.SQLIntegrityConstraintViolationException:ORA-00001:唯一约束当用户输入数据库中已经存在的id时，我想在index.jsp中显示一个错误注释 <%@ pa

我有一个

index.jsp

页面，从中我将名称和id插入到oracle表中。我能够成功插入，但当用户再次输入相同的员工id时，

index.jsp

页面将重定向到tomcat错误页面

HTTP Status 500 javax.servlet.ServletException:java.sql.SQLIntegrityConstraintViolationException:ORA-00001:唯一约束

当用户输入数据库中已经存在的id时，我想在

index.jsp

中显示一个错误注释

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body><center>
  <H1>Inserting record into a Database</H1>
       <%@ page language="java" %>
        <%@ page import="java.sql.*" %>
         <%@ page import="java.sql.DriverManager.*" %>

            <% 
        int flag=0;
        PreparedStatement ps=null;
        Connection con= null;
        ResultSet rs= null;
        Class.forName("oracle.jdbc.driver.OracleDriver");
        con=DriverManager.getConnection("hostname","user","admin");
        Statement st=con.createStatement();

            String id = request.getParameter("id");  
            String name= request.getParameter("name");


            ResultSet resultset = 
                    rs=st.executeQuery("INSERT INTO employee (employeeid,employeename)VALUES ('"+id+"','"+name+""); 
            out.println("Data is successfully inserted!");

       %> 
 </center>           
</body>
</html>


在此处插入标题
将记录插入数据库

当控件转到catch块处理异常并显示要显示的消息时，将代码括在try-and-catch块中。

更具体地说，处理异常SQLIntegrityConstraintViolationException。此异常表示违反了完整性约束（外键、主键或唯一键）

try{
    int flag=0;
    PreparedStatement ps=null;
    Connection con= null;
    ResultSet rs= null;
    Class.forName("oracle.jdbc.driver.OracleDriver");
    con=DriverManager.getConnection("hostname","user","admin");
    Statement st=con.createStatement();

        String id = request.getParameter("id");  
        String name= request.getParameter("name");


        ResultSet resultset = 
                rs=st.executeQuery("INSERT INTO employee (employeeid,employeename)VALUES ('"+id+"','"+name+""); 
        out.println("Data is successfully inserted!");

   }catch(SQLIntegrityConstraintViolationException e ){
        //Duplicate entry '' for key 'PRIMARY'
        System.out.println(e.getMessage());//you can modify the output as per your requirement.
   } catch (Exception e) {
        e.printStackTrace();
   }

更具体地说，处理异常SQLIntegrityConstraintViolationException。此异常表示违反了完整性约束（外键、主键或唯一键）

try{
    int flag=0;
    PreparedStatement ps=null;
    Connection con= null;
    ResultSet rs= null;
    Class.forName("oracle.jdbc.driver.OracleDriver");
    con=DriverManager.getConnection("hostname","user","admin");
    Statement st=con.createStatement();

        String id = request.getParameter("id");  
        String name= request.getParameter("name");


        ResultSet resultset = 
                rs=st.executeQuery("INSERT INTO employee (employeeid,employeename)VALUES ('"+id+"','"+name+""); 
        out.println("Data is successfully inserted!");

   }catch(SQLIntegrityConstraintViolationException e ){
        //Duplicate entry '' for key 'PRIMARY'
        System.out.println(e.getMessage());//you can modify the output as per your requirement.
   } catch (Exception e) {
        e.printStackTrace();
   }

使用

try catch

块处理异常

要防止它出现，您可以做的是检查该记录是否已经存在于表中

如果存在相同的

id

，则不要执行插入操作

try{
        int flag=0;
        PreparedStatement ps=null;
        Connection con= null;
        ResultSet rs= null;
        Class.forName("oracle.jdbc.driver.OracleDriver");
        con=DriverManager.getConnection("hostname","user","admin");
        Statement st=con.createStatement();

        String id = request.getParameter("id");  
        String name= request.getParameter("name");

        // Check if the "id" is already present in table or not
        rs = st.executeQuery("SELECT * FROM employee WHERE employeeid" = id );   
        if (!rs.next() ) {

            // id is not present then insert the new record
            rs = st.executeQuery("INSERT INTO employee (employeeid,employeename)VALUES ('"+id+"','"+name+""); 
            System.out.println("Data is successfully inserted!");

        } else{

            // id is already present then show the error message
            System.out.println("Data is already present in table!");
        }

} catch(Exception e){

    // Handle any other exception occuring 
    System.out.println("Exception : " + e.printStackTrace());
}

使用

try catch

块处理异常

要防止它出现，您可以做的是检查该记录是否已经存在于表中

如果存在相同的

id

，则不要执行插入操作

try{
        int flag=0;
        PreparedStatement ps=null;
        Connection con= null;
        ResultSet rs= null;
        Class.forName("oracle.jdbc.driver.OracleDriver");
        con=DriverManager.getConnection("hostname","user","admin");
        Statement st=con.createStatement();

        String id = request.getParameter("id");  
        String name= request.getParameter("name");

        // Check if the "id" is already present in table or not
        rs = st.executeQuery("SELECT * FROM employee WHERE employeeid" = id );   
        if (!rs.next() ) {

            // id is not present then insert the new record
            rs = st.executeQuery("INSERT INTO employee (employeeid,employeename)VALUES ('"+id+"','"+name+""); 
            System.out.println("Data is successfully inserted!");

        } else{

            // id is already present then show the error message
            System.out.println("Data is already present in table!");
        }

} catch(Exception e){

    // Handle any other exception occuring 
    System.out.println("Exception : " + e.printStackTrace());
}

这更倾向于应用程序的体系结构实现。未在应用程序中实现验证的典型问题。您是否实现了验证？您应该避免在表示层使用java代码：使用java

try。。catch..finally

要处理错误并确保连接状态正确，请关闭它。下面的任何答案是否解决了您的问题？如果是的话，那么你可以接受它，这样对其他有同样问题的人会有好处。这更倾向于应用程序的架构实现。未在应用程序中实现验证的典型问题。您是否实现了验证？您应该避免在表示层使用java代码：使用java

try。。catch..finally

要处理错误并确保连接状态正确，请关闭它。下面的任何答案是否解决了您的问题？如果是，那么你可以接受它，这样对其他有同样问题的人会有好处。谢谢Prakash。。这对我很有用…它对我有用。。很抱歉，由于我过去一周不在城里，所以回复太晚：）。谢谢Prakash。。这对我很有用…它对我有用。。很抱歉，由于过去一周我不在城里，所以回复太晚：）。谢谢Rohit。。。我试着使用这个异常处理方法，它奏效了…谢谢你。。。我试着使用这个异常处理方法，它奏效了。。