我被困在一个 Java 程序中。 我的程序是一对多右外连接

Question

I am stuck in a Java program. My program is One To Many Right Outer Join. I am trying to figure where my error is, but I couldn't find it by myself.

I tried to solve it so many times, but nothing happened.

I tried to change the database column name, it didn't work. I tried to debug using Eclipse debugger, couldn't find any.

Details are attached below.

MainClass.java

package OneToManyRightJoin;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

public class MainClass {

    public static void main(String[] args) {
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            Connection con =DriverManager.getConnection("jdbc:mysql://localhost:3306/person","root","1234");
            Statement st=con.createStatement();
            java.sql.Statement st1=con.createStatement();
            java.sql.Statement st2=con.createStatement();
            
            String query1 ="SELECT * from person" ;
            String query2 ="SELECT * from address" ;
            
            ResultSet rs1=st1.executeQuery(query1);
            ResultSet rs2=st2.executeQuery(query2);   
    
    //for address   
            
            List<Address> addrList = new ArrayList<Address>();
            List<Person> personList = new ArrayList<Person>();
            
            while(rs1.next()) 
            {
            
              
            //List<Address> addrList = new ArrayList<Address>();     
                Address a=new Address();
                
                a.setPid(rs1.getInt("pid"));
                a.setAid(rs1.getInt("Aid"));
                a.setAddress1(rs1.getString("Ad1"));
                a.setAddress2(rs1.getString("Ad2"));
                addrList.add(a);
                
            }
     

    while(rs2.next()) 
    {
        Person p=new Person();
        p.setPid(rs2.getInt("pid")) ;
        p.setName(rs2.getString("name"));
        personList.add(p);
    }   
    
    //comparing 2 List(personList and addrList)
    
    List matchedList=new ArrayList<List>();
    
    for(int i=0;i<addrList.size();i++)
    {
        List innerPersonList = new ArrayList();
         
        Address pkgInnerAddress = (Address)addrList.get(i);
        
        for(int j=0;j<personList.size();j++)
        
        {                     
            
            if(addrList.get(i).getPid() == personList.get(j).getPid())         
            
            {
                Person innerPerson = personList.get(j);
                
                innerPersonList.add(innerPerson);
      
        }   
                                       
        
        }
   
       // add the list of matched addresses to person
       pkgInnerAddress.setLst(innerPersonList);
     
       matchedList.add(pkgInnerAddress);
       
    }   
   
 
  
    
 System.out.println("Right Outer join details" +"\n");
       
        for (int i=0; i<matchedList.size(); i++) {
            
            Address a = (Address)matchedList.get(i);
            
            System.out.println("\n" + "address details Id Ad1 Ad2 are "+a.getAid()+" "+a.getAddress1()+" "+a.getAddress2()+" "+a.getPid()+"\n");
            
        
            
            for (int j=0; j<a.getLst().size(); j++) {
                
                System.out.println(" Person Pid is " +a.getLst().get(j).getPid());  
            }
        
        }
    }
                   
catch (SQLException e)
    {
        System.out.println(e);          
    }   
    catch(ClassNotFoundException e1)
    {
        System.out.println(e1);     
}
}
}

Address.java

package OneToManyRightJoin;

import java.util.List;

public class Address {
    
    int aid;
    int Pid;
    String Address1;
    String Address2;
    List<Person>lst;
    public int getAid() {
        return aid;
    }
    public void setAid(int aid) {
        this.aid = aid;
    }
    public int getPid() {
        return Pid;
    }
    public void setPid(int pid) {
        Pid = pid;
    }
    public String getAddress1() {
        return Address1;
    }
    public void setAddress1(String address1) {
        Address1 = address1;
    }
    public String getAddress2() {
        return Address2;
    }
    public void setAddress2(String address2) {
        Address2 = address2;
    }
    public List<Person> getLst() {
        return lst;
    }
    public void setLst(List<Person> lst) {
        this.lst = lst;
    }
}

Person.java

package OneToManyRightJoin;

public class Person 
{
    int pid;
    String Name;
    
    Person()
    {
        
    }

    public int getPid() {
        return pid;
    }

    public void setPid(int pid) {
        this.pid = pid;
    }

    public String getName() {
        return Name;
    }

    public void setName(String name) {
        Name = name;
    }
}

These are my database details images.

Address DB Person DB

Error Details:

Error Details

Answer 1

You are facing error at this line:

a.setAid(rs1.getInt("Aid"));

The reason is you are setting the value of particular column in this scenario you are setting value of object a with Aid column. But SQL says that Aid column you are using which is not presented it means you doesn't have any column which has name Aid into your database table.