使用 Java 将用户数据插入数据库时出现问题

Question

我有一个包含电影 table 的数据库，我正在尝试编写一个 java 程序来接收用户的输入并将其插入数据库。我的代码如下。我已经包含了整个代码，因为我不确定为什么会出现错误。

对于我收到的每一行 stmt.set...，例如：

error: cannot find symbol - stmt.setString(fname);

我不明白为什么我会得到这个，因为我已经收到了用户的输入并在插入之前将其分配给了这个变量。

非常感谢任何帮助。谢谢！

import java.sql.*;
import java.util.*;
import java.io.*;

public class insert {
    public static void main(String [] argv) throws Exception {
        Connection conn = null;
        try
        {
            Class.forName("org.postgresql.Driver");
            String url = "jdbc:postgresql://localhost//////";
            conn = DriverManager.getConnection(url, "/////", "///");
        }
        catch (ClassNotFoundException e)
        {
            e.printStackTrace();
            System.exit(1);
        }
        catch (SQLException e)
        {
            e.printStackTrace();
            System.exit(2);
        }
        BufferedReader bufRead = new BufferedReader(new InputStreamReader(System.in));
        try {
            System.out.println("Please enter the id for the new movie: ");
            String id = bufRead.readLine();
            int id_int = Integer.parseInt(id);
            System.out.println("Please enter the title for the new movie: ");
            String title = bufRead.readLine();
            System.out.println("Please enter the director's first name: ");
            String fname = bufRead.readLine();
            System.out.println("Please enter the director's last name: ");
            String lname = bufRead.readLine();
            System.out.println("Please enter the genre of the movie: ");
            String genre = bufRead.readLine();
            System.out.println("Please enter the media type: ");
            String media = bufRead.readLine();
            System.out.println("Please enter the movie's release date: ");
            String date = bufRead.readLine();
            java.sql.Date release_d = java.sql.Date.valueOf(date);
            System.out.println("Please enter the movie's studio: ");
            String studio = bufRead.readLine();
            System.out.println("Please enter the retail price of the movie: ");
            String price = bufRead.readLine();
            double price_d = Double.parseDouble(price);
            System.out.println("Please enter the number of copies in stock: ");
            String stock = bufRead.readLine();
            int stock_int = Integer.parseInt(stock);

        } catch (IOException err) {
            System.out.println(err);
        } catch (NumberFormatException err) {
            System.out.println(err);
        }

        System.out.println("\nWelcome to MovieDirect");
        System.out.println();

        try {
            PreparedStatement stmt = conn.prepareStatement("INSERT INTO movie " + "(movie_id, movie_title, director_first_name, director_last_name, genre, media_type, release_date, studio_name, retail_price, current_stock)" + "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)");

            stmt.setInt(1, id_int);
            stmt.setString(2, title);
            stmt.setString(3, fname);
            stmt.setString(4, lname);
            stmt.setString(5, genre);
            stmt.setString(6, media);
            stmt.setDate(7, release_d);
            stmt.setString(8, studio);
            stmt.setDouble(9, price_d);
            stmt.setString(10, stock_int);

            stmt.executeUpdate();

        } catch (SQLException e) {
            System.out.println(e);
            conn.close();
            System.exit(1);
        }
        System.out.println("\nSuccess! ");
        conn.close();
    }
}

Answer 1

乍一看，你的错误看起来像是在谈论 setString 等等，但它实际上是关于你传递给那些方法的变量。

所有变量id_int、title、fname、lname等都在不同的作用域[=27]中声明=]：另一个try块。

要修复它，请在 try 块之外声明所有这些变量（就像您对 conn 所做的那样），以便它们在所有 try块。

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