英文:
Duplicate entry for primary key - registration form
问题
我有一个简单的JSP、Servlet和MySQL注册表单。但是，我只能注册一个用户，然后出现以下错误：
严重：消息：键'PRIMARY'的重复条目'1'。
当然，当我从数据库中删除该用户后，我可以再次创建，但只能创建一个用户。此外，我在该列上设置了自动递增：
CREATE TABLE user (id int(3) NOT NULL AUTO_INCREMENT ...
这也是我的数据库插入方法：
public class UserDAO {public int registerUser(User User) throws ClassNotFoundException, SQLException {String INSERT_USERS_SQL = "INSERT INTO user"+ " (id, firstName, lastName, username, password, email) VALUES "+ " (?, ?, ?, ?, ?, ?)";int result = 0;Class.forName("com.mysql.jdbc.Driver");try (Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/cs230projekat","root","");// Step 2:Create a statement using connection objectPreparedStatement preparedStatement = connection.prepareStatement(INSERT_USERS_SQL)) {preparedStatement.setInt(1, 1);preparedStatement.setString(2, User.getFirstName());preparedStatement.setString(3, User.getLastName());preparedStatement.setString(4, User.getUsername());preparedStatement.setString(5, User.getPassword());preparedStatement.setString(6, User.getEmail());System.out.println(preparedStatement);// Step 3: Execute the query or update queryresult = preparedStatement.executeUpdate();} catch (SQLException e) {// process sql exceptionprintSQLException(e);}return result;}}
谢谢。
英文:
I have one simple registraton form with jsp, servlet and mysql. But, I can register only one user, then i got this error:
Severe: Message: Duplicate entry '1' for key 'PRIMARY'. Of course, when I delete that user from database I can create again but just one user. Also, I put auto increment on that column:
CREATE TABLE user (id int(3) NOT NULL AUTO_INCREMENT ...
This is also my method for insert in db:
public class UserDAO {public int registerUser(User User) throws ClassNotFoundException, SQLException {String INSERT_USERS_SQL = "INSERT INTO user"+ " (id, firstName, lastName, username, password, email) VALUES "+ " (?, ?, ?, ?, ?, ?)";int result = 0;Class.forName("com.mysql.jdbc.Driver");try (Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/cs230projekat","root","");// Step 2:Create a statement using connection objectPreparedStatement preparedStatement = connection.prepareStatement(INSERT_USERS_SQL)) {preparedStatement.setInt(1, 1);preparedStatement.setString(2, User.getFirstName());preparedStatement.setString(3, User.getLastName());preparedStatement.setString(4, User.getUsername());preparedStatement.setString(5, User.getPassword());preparedStatement.setString(6, User.getEmail());System.out.println(preparedStatement);// Step 3: Execute the query or update queryresult = preparedStatement.executeUpdate();} catch (SQLException e) {// process sql exceptionprintSQLException(e);}return result;}
Thank you.
答案1
得分: 4
你总是通过preparedStatement.setInt(1, 1)将id列的值设置为1。既然你说id列是自增的，请从你的SQL中移除id，删除上述行，并调整所有其他setString()方法调用的列索引（第一个参数）。
英文:
You are always setting the value of your id column to 1 via preparedStatement.setInt(1, 1). Since you say you have an auto-increment on the id column, remove id from your SQL, remove the aforementioned line and adjust the column indexes (first arguments) for all the other setString() method calls.
答案2
得分: 1
自动递增设置后，您无需在SQL插入语句中指定 'id' 列。
这是关于MySQL官方网站上自动递增的一些信息：https://dev.mysql.com/doc/refman/8.0/en/example-auto-increment.html
英文:
With auto increment set you don’t have to specify the ‘id’ column in your sql insert statements.
Here’s some information on the auto increment from MySQL’s website: https://dev.mysql.com/doc/refman/8.0/en/example-auto-increment.html
答案3
得分: 0
从您的代码看，似乎您总是为id列插入值1，请正确实现autoGenerate。有关更多帮助，您可以查看类似的实现。
英文:
From your code it looks like you are inserting the value 1 always for the id column, try implementing the autoGenerate properly. For more help, you can have a look on similar implementation
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