JDBC insert query does not update mysql database
Question
The following code does not insert a row into the corresponding table. I have already tested the db connection and ran the query in the database, both of which have passed however when I add inputs via a .jsp form the values are still not inserting.
public class UserDao {
public String registerUser(User user){
String username = user.getUsername();
String email = user.getEmail();
String password = user.getPassword();
Connection con;
con = DBConnection.createConnection();
PreparedStatement preparedStatement;
try{
con.setAutoCommit(false);
String query = ("INSERT INTO user (username, email, password, user_id) VALUES(?, ?, ?, ?)");
preparedStatement = con.prepareStatement(query);
preparedStatement.setString(1, username);
preparedStatement.setString(2, email);
preparedStatement.setString(3, password);
preparedStatement.setString(4,null);
int i = preparedStatement.executeUpdate();
con.commit();
preparedStatement.close();
con.close();
if(i !=0 ){
return "SUCCESS";
}
}catch(SQLException e){
throw new RuntimeException(e);
}
return "Something is wrong!";
}
}
For reference here is what my servlet class and .jsp file looks also like:
public class UserRegistrationServlet extends HttpServlet {
public UserRegistrationServlet(){}
/**
* Handles the HTTP <code>POST</code> method.
*
* @param request servlet request
* @param response servlet response
* @throws ServletException if a servlet-specific error occurs
* @throws IOException if an I/O error occurs
*/
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String userName = request.getParameter("username");
String email = request.getParameter("email");
String password = request.getParameter("password");
User user = new User();
user.setUsername(userName);
user.setEmail(email);
user.setPassword(password);
UserDao userDao = new UserDao();
String userRegistered = userDao.registerUser(user);
if(userRegistered.equals("SUCCESS")){
request.getRequestDispatcher("test.jsp").forward(request, response);
}else{
request.setAttribute("error", userRegistered);
request.getRequestDispatcher("/UserRegistration.jsp").forward(request, response);
}
}
}
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Register</title>
<script>
function validate()
{
var username = document.form.username.value;
var email = document.form.email.value;
var password = document.form.password.value;
var conpassword= document.form.conpassword.value;
if (username==null || username=="")
{
alert("Full Name can't be blank");
return false;
}
else if (email==null || email=="")
{
alert("Email can't be blank");
return false;
}
else if(password.length<6)
{
alert("Password must be at least 6 characters long.");
return false;
}
else if (password!=conpassword)
{
alert("Confirm Password should match with the Password");
return false;
}
}
</script>
</head>
<body>
<center><h2>Java Registration application using MVC and MySQL </h2></center>
<form name="form" action="UserRegistrationServlet" method="post" onsubmit="return validate()">
<table align="center">
<tr>
<td>Username</td>
<td><input type="text" name="username" /></td>
</tr>
<tr>
<td>Email</td>
<td><input type="text" name="email" /></td>
</tr>
<tr>
<td>Password</td>
<td><input type="password" name="password" /></td>
</tr>
<tr>
<td>Confirm Password</td>
<td><input type="password" name="conpassword" /></td>
</tr>
<tr>
<td><%=(request.getAttribute("errMessage") == null) ? ""
: request.getAttribute("errMessage")%></td>
</tr>
<tr>
<td></td>
<td><input type="submit" value="Register"></input><input
type="reset" value="Reset"></input></td>
</tr>
</table>
</form>
</body>
</html>
Not sure where the error in my code, so any advice will be very helpful. Thanks
Updates:
[![After throwing a runtime exception ][2]][2]
1 answers
solution1
3 ACCPTED 2019-03-11 22:43:23
You're setting user_id to null and the database complains that the column must not be null . I assume that you haven't passed null to the statement you tested against the DB directly, so that you were setting an empty string instead (or the table is to set a default or automatically generated value in case it's missing).
If there is a default value or a autogenerated one, you can simply leave away user_id in your insert statement and it should work.
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.