java.sql.Sqlexception: Column 'id' not found

Question

My code to search in the BD by id. The class is ContatoDao:

    //Pesquisa por id
public Contato pesquisaId(int id) {
    
    
    String sql = "select nome from contatos where id = "+id;
    Contato contato = null;
    
    try {
        PreparedStatement stmt = this.connection.prepareStatement(sql);
        ResultSet rs = stmt.executeQuery(sql);
        
        if(rs.next()) {
            contato = new Contato();
            contato.setId(rs.getLong("id"));
            contato.setNome(rs.getString("nome"));
            contato.setEmail(rs.getString("email"));
            contato.setEndereco(rs.getString("endereco"));
        }
        rs.close();
        stmt.close();
        //return contato;
        
    } catch (SQLException e) {
        //throw new DAOException("Erro ao pesquisar no banco de dados pelo id.");
        throw new RuntimeException(e);
    }
    return contato;
    
}

This other code is the test class code of this code above:

    package br.com.caelum.jdbc.teste;

import br.com.caelum.jdbc.dao.ContatoDao;
import br.com.caelum.jdbc.modelo.Contato;

public class TestaPesquisaId {

    public static void main(String[] args) {

        ContatoDao dao = new ContatoDao();
        Contato contato = dao.pesquisaId(1);
        
        System.out.println("Nome: "+contato.getNome());
        
    }

}

This is the error that shows on the console:

 Exception in thread "main" java.lang.RuntimeException: java.sql.SQLException: Column 'id' not found.
    at br.com.caelum.jdbc.dao.ContatoDao.pesquisaId(ContatoDao.java:101)
    at br.com.caelum.jdbc.teste.TestaPesquisaId.main(TestaPesquisaId.java:11)
Caused by: java.sql.SQLException: Column 'id' not found.
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129)
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97)
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:89)
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:63)
    at com.mysql.cj.jdbc.result.ResultSetImpl.findColumn(ResultSetImpl.java:556)
    at com.mysql.cj.jdbc.result.ResultSetImpl.getLong(ResultSetImpl.java:829)
    at br.com.caelum.jdbc.dao.ContatoDao.pesquisaId(ContatoDao.java:90)
    ... 1 more

One detail: This id yes there in the bank, inserted with the method inserirContato that I created.

Answer 1

The text of his query does not have the column id, only the nome. All the fields you want to get should be on SELECT:

...
String sql = "select id, nome from contatos where id = " + id;
...

Another point is what the hkotsubo commented. Use the field as a parameter instead of concatenating in query:

...
stmt.setInt(1, id);
ResultSet rs = stmt.executeQuery("select id, nome from contatos where id = ?");
...