英文:
SEVERE: null error com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException
问题
以下是翻译后的内容：
我在关于“SEVERE”错误的问题上反复出现错误，我尝试更改请求的语法，但是即使更改后，我仍然会遇到错误，并且它们的请求似乎是错误的。你有解决方案吗？
这是我的错误：
2020年5月29日 下午4:26:02 javaapplicationhotel2.Login_Form jButton_LoginActionPerformed
SEVERE: null
com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: 在你的SQL语法中存在一个错误；请查阅适用于你的MariaDB服务器版本的手册，以获取关于正确使用语法的说明，附近的内容为“'users' WHERE 'username' = 'nom d'utilisateur' AND 'password' = ''”（位于第1行）
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
...
这是我的代码，用于打开登录页面，通过点击登录按钮而不输入任何内容，应该显示代码中的错误消息，但实际上我得到了上面的错误。
PreparedStatement st;
ResultSet rs;
// 获取用户名和密码
String username = jTextField_Username.getText();
String password = String.valueOf(jPasswordField.getPassword());
// 查询语句，用于检查是否存在相应的用户名和密码
String query = "SELECT * FROM 'users' WHERE 'username' = ? AND 'password' = ?";
try {
st = (PreparedStatement) Connecter.getConnection().prepareStatement(query);
st.setString(1, username);
st.setString(2, password);
rs = st.executeQuery();
if(rs.next())
{
// 打开管理页面
Gestionnaire form = new Gestionnaire();
form.setVisible(true);
form.pack();
form.setLocationRelativeTo(null);
this.dispose();
}else{
// 错误提示
JOptionPane.showMessageDialog(null, "Invalid username/password", "Authentication Error", 2);
}
} catch (SQLException ex) {
java.util.logging.Logger.getLogger(Login_Form.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
注意：这里的代码片段中可能存在错误，因为我只是翻译了你提供的代码。如果出现问题，你需要仔细检查代码逻辑和语法。
英文:
I have a recurring error vis-à-vis my "SEVERE", I ask myself to change the syntax of my request but even by changing I always have an error and their requests seem false. Do you have a solution
here my error:
mai 29, 2020 4:26:02 PM javaapplicationhotel2.Login_Form jButton_LoginActionPerformed
SEVERE: null
com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ''users' WHERE 'username' = 'nom d\'utilisateur' AND 'password' = ''' at line 1
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:500)
at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:481)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.Util.getInstance(Util.java:386)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1052)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3609)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3541)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2002)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2163)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2624)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2127)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:2293)
at javaapplicationhotel2.Login_Form.jButton_LoginActionPerformed(Login_Form.java:428)
at javaapplicationhotel2.Login_Form$8.actionPerformed(Login_Form.java:204)
at java.desktop/javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1967)
at java.desktop/javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2308)
at java.desktop/javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:405)
at java.desktop/javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:262)
at java.desktop/javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:279)
at java.desktop/java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:297)
at java.desktop/java.awt.Component.processMouseEvent(Component.java:6636)
at java.desktop/javax.swing.JComponent.processMouseEvent(JComponent.java:3342)
at java.desktop/java.awt.Component.processEvent(Component.java:6401)
at java.desktop/java.awt.Container.processEvent(Container.java:2263)
at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:5012)
at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2321)
at java.desktop/java.awt.Component.dispatchEvent(Component.java:4844)
at java.desktop/java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4918)
at java.desktop/java.awt.LightweightDispatcher.processMouseEvent(Container.java:4547)
at java.desktop/java.awt.LightweightDispatcher.dispatchEvent(Container.java:4488)
at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2307)
at java.desktop/java.awt.Window.dispatchEventImpl(Window.java:2762)
at java.desktop/java.awt.Component.dispatchEvent(Component.java:4844)
at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:772)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:721)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:715)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:95)
at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:745)
at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:743)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:742)
at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)
here my code here my code which is used to open a login page, by clicking on loggin without writing anything, this should display the error message present in my code, but instead I have this error above
PreparedStatement st;
ResultSet rs;
// donnez l'username et le password
String username = jTextField_Username.getText();
String password = String.valueOf(jPasswordField.getPassword());
// requete indiquant si les identifiants existent
String query = "SELECT * FROM 'users' WHERE 'username' = ? AND 'password' = ?";
try {
st = (PreparedStatement) Connecter.getConnection().prepareStatement(query);
st.setString(1, username);
st.setString(2, password);
rs = st.executeQuery();
if(rs.next())
{
//ouvrir le gestionnaire
Gestionnaire form = new Gestionnaire();
form.setVisible(true);
form.pack();
form.setLocationRelativeTo(null);
this.dispose();
}else{
//erreur
JOptionPane.showMessageDialog(null, " Nom de compte / mot de passe invalide", "Erreur d'authentification",2);
}
} catch (SQLException ex) {
java.util.logging.Logger.getLogger(Login_Form.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
专注分享java语言的经验与见解，让所有开发者获益！
评论