Question

我无法用mysql弄清楚我的语法错误。

我在eclipse中的Java程序中运行登录屏幕并收到此错误消息：

com.mysql.jdbc.exceptions.MySQLSyntaxErrorException：您有错误在你的SQL语法中;查看与MySQL对应的手册服务器版本，用于在＃C; f8d6792＆＃39;＆＃39; [C @ f8d6792＆＃39;＆＃39;在线 1

每次运行程序C@后更改7个字符并抛出异常。我试着查看手册，但过了一会儿就气馁了。

以下是抛出异常的部分的代码：

Connection conn = null;
String dbName = "test";
String serverip = "localhost";
String serverport = "3306";
String url = "jdbc:mysql://" + serverip + ":" + serverport + "/" + dbName;
String driver = "com.mysql.jdbc.Driver";
String databaseUserName = "root";
String databasePassword = "Pitbu!1s";
Statement stmt = null;
ResultSet rs = null;
String sql = "select * from users where user_name = '" + textField_UserName.getText() + " AND password = '" + passwordField_Password.getPassword().toString() + "'";

try {
  Class.forName(driver);
  conn = DriverManager.getConnection(url, databaseUserName, databasePassword);
  stmt = conn.createStatement();
  rs = stmt.executeQuery(sql);

  if (rs.next())

    lblUserName_Label.setText(textField_UserName.getText());
  lblUserNameOver_Label.setText(textField_UserName.getText() + "'s");
  textField_UserName.setText("");
  passwordField_Password.setText("");
  panel_Main.setVisible(true);
  panel_LogIn.setVisible(false);

  conn.close();
} catch (Exception i) {
  System.out.print(i);
}

Answer 1

你错过了SQL语句中的撇号

String sql = "select * from users where user_name = '" + textField_UserName.getText() + "' AND password = '" + passwordField_Password.getPassword().toString() + "'";

Answer 2

可能问题出在这里：

String sql = "select * from users where user_name = '" + textField_UserName.getText() + " AND password = '" + passwordField_Password.getPassword().toString() + "'";
                                                                                         ^

您没有关闭userName的引号，很可能是构建了此查询：

select * from users where user_name = 'tom AND password='pw';
                                          ^

为了完成这项工作，你可以添加缺失的引用，就是这样。

更好的方法是不连接字符串并使用参数来构建查询。这将更安全，更易于维护。

您的SQL语法有错误; ......附近＆＃39; [C @ f8d6792＆＃39;＆＃39;在第1行

2 个答案: