java - JDBC 插入查询不在数据库中插入记录

Question

我有个小问题。我的数据库不工作，我不知道为什么..没有错误。一切看起来都很好，我正在输入值，我的网络应用程序说“已保存到数据库中”，但事实并非如此。数据库为空。这是我的代码:

public class ConnectionManager {

    private static String dbURL = "jdbc:derby://localhost:1527/CarRental";
    private static Connection conn = null;
    private static Statement stmt = null;

    public void createConnection() {
        try {
            Class.forName("org.apache.derby.jdbc.ClientDriver").newInstance();
            conn = DriverManager.getConnection(dbURL,"GioRgio","12345");
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    public void addClient(Klienci klienci) {

        String query = "INSERT INTO KLIENCI"
                + "(ID, IMIE, NAZWISKO, ADRES, TELEFON, MAIL)"
                + " VALUES (" + klienci.getId_klienta() + ",'" + klienci.getImie() + "','" 
                + klienci.getNazwisko() + "'," + klienci.getAdres()+"',"+klienci.getTelefon()+"',"+klienci.getMail() + ")"; 

        try {
            stmt = conn.createStatement();
            stmt.executeUpdate(query);
            stmt.close();
        } catch (SQLException sqlExcept) {
            sqlExcept.printStackTrace();
        }
    }
    public void closeConnection() {
        try {
            if (stmt != null) {
                stmt.close();
            }
            if (conn != null) {
                DriverManager.getConnection(dbURL + ";shutdown=true");
                conn.close();
            }
        } catch (SQLException sqlExcept) {
        }

    }
}

Answer 1

问题的直接原因似乎是 INSERT 语句(地址)中的文字转义不正确。我们可以尝试解决这个问题，但使用准备好的语句会更好，它会自行处理转义。

String sql = "INSERT INTO KLIENCI (ID, IMIE, NAZWISKO, ADRES, TELEFON, MAIL) ";
sql += "VALUES (?, ?, ?, ?, ?, ?,)";
PreparedStatement ps = conn.prepareStatement(sql);
ps.setInt(1, klienci.getId_klienta());
ps.setString(2, klienci.getImie());
ps.setString(3, klienci.getNazwisko());
ps.setString(4, klienci.getAdres());
ps.setString(5, klienci.getTelefon());
ps.setString(6, klienci.getEmail());

ps.executeUpdate();