mysql - 无法将数据插入我的数据库

Question

我是 Struts2 的新手。我创建了一些类文件来将数据插入数据库(MySQL)。当我插入数据时出现错误。错误是

java.sql.SQLException: Parameter index out of range (1 > number of parameters, which is 0).

我无法理解它是如何发生以及如何解决它。

RegistrationService.java

 PreparedStatement p = con.prepareStatement(sql);   
                        sql = "insert into registration(first_name,last_name) value(?,?)";
                            p.setString(1,registration.first_name);
                            p.setString(2,registration.last_name);

注册.java

    public class Registration extends ActionSupport{
       String  first_name;
       String last_name;
//getter and setter

RegistrationAction.java

public String execute() throws ClassNotFoundException, SQLException{
    RegistrationService registrationservice= new RegistrationService();
    if(registrationservice.filledRegistration(registration)){
    return "registered";
    }
    return "failed";

Answer 1

我认为你错过了这一行:

PreparedStatement p = con.prepareStatement(sql);

sql = "insert into registration(first_name,last_name) value(?,?)";

要更正它，请参阅下文:

sql = "insert into registration(first_name,last_name) value(?,?)";

PreparedStatement p = con.prepareStatement(sql);