Question

当我以用户身份写一个名字时，我需要访问已存在于数据库中的此名称的姓氏。例如：

[{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":{"airplaneDetail":{"flight":

当我执行我的代码时，我看不到任何姓氏作为输出。

在我的数据库中，我有Enter a name: beste beste's surname is: ozcaglar，name和surname（自动增量）列。

no

Answer 1

你可以这样说：

import java.sql.*;
import java.util.*;
public class test4 {
public static void main(String[] args) {
    @SuppressWarnings("resource")
    Scanner scan = new Scanner(System.in);
    System.out.println("Enter a name: ");
    String isim = scan.next();
    try {
            Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/test", "root", "");
            System.out.println("Connection success");
            String query = "SELECT * FROM users WHERE surname='" + isim + "'";
            Statement stm = conn.createStatement();
            ResultSet rs = stm.executeQuery(query);
            while (rs.next()) {
                String fName = rs.getString(1);
                String sName = rs.getString(2);
                System.out.println("Name: " + fName + " Surname: " + sName);
            }
        } catch (Exception e) {
        System.err.println("Error");
        }
    }
}

Answer 2

该错误表示该表没有名为＆＃34; isim＆＃34;的列。

也许你打算写：

SELECT surname FROM student_table WHERE name='isim'

编辑（评论后）：

query = "SELECT surname FROM student_table WHERE name='" + isim + "'"

但是出于安全原因，它不应该在实际应用程序中使用（它允许SQL注入攻击）。

在实际的生产代码中，您应该转义输入字符串，或使用参数化查询......

如何使用Java访问MySQL中的特定行

2 个答案: