What is better is always complicated to assert without a specific context.People think that creating connections costs expensive and that there will be a complicated process. At least that's what I imagine, I'm not in their head. I know that many use this premise, but it may be that they are only copying what they saw wrong there.The fact is that the connection object is a pool, it delivers you a connection according to your need and knows how to manage the connections, and it is a well-thought and developed object by people who understand how to do. Everything works perfectly, with performance in a simplified way.It is even possible to create a simple abstraction to simplify something specific, but to create a Singleton, or a replacement for the connection, as I see in almost all the codes that the staff put here, is absurd, is a antipattern. It is a person who little or nothing understands the subject trying to create something certainly worse for little or no gain.So the two cases presented seem to be wrong. Of course, I didn't see that class. AcessoBancobut almost everyone does wrong.These reported problems probably occur because it is implementing wrong. And the right thing is not to implement any of this. It begins to create new problems to solve the problems that should never exist. If it was necessary an abstraction of this type for any application the .NET would provide. Never implement anything that cannot justify with property.I believe that the problem occurs because people try to create design patterns without even understanding what problem it is solving, this includes DAO or repository, in general it is quite complicated to do right, and almost always does not give the benefit that the person thinks will give, it is just doing what "ever" is doing, without understanding how to do.By the comment it seems not to make sense to have a Singleton, after all it has different connections, it is plural and not singular.

Looking at this, a possible error in the code is that at the time of creating your Combustive() object, it is not finding the field Fuel Supplyed. Try to run the procedure in the bank and check if all columns are coming correctly named, usually in the use of Sum() the column comes as "(In the column name)". Try adding a name to the sum column in the select, it would look like this: ALTER PROCEDURE [dbo].[RelatorioDcv] @dateInicio date, @dataFim date as begin select ve.Placa, sum(m.CombustivelAbastecido) as CombustivelAbastecido, count(v.VrId) from Vr v inner join Mv m on v.IdMv = m.Id inner join Veiculo ve on v.IdVeiculo = ve.Id inner join Combustivel c on ve.IdCombustivel = c.IdCombustivel where convert(Date,v.DataEHoraServico) between @dateInicio and @dataFim group by ve.Placa end

You can call the X.php file in Y.php the way you will use depends on how you want to use the X.php file You can use: include 'X.php'; require 'X.php'; require_once 'X.php';The choice of the method to use is yours but basically it refers to the treatment of errors, in include it only displays a warning and continues the execution of the script, in require it for the execution if you give some error in the code

You can try this too: // método getLista() ... contato.setTamanho(Tamanho.valueOf(objetoResultSet.getString("size"))); As https://pt.stackoverflow.com/questions/278955/enum-retorna-null-do-banco#comment569971_278969 as in your table has null value in some records this causes the NullPointerException error when assigning in your enum. A way around this error could only seek records with different size of null. select * from contatos where size != null

To show the field needs to be inside a "foreach"example:<?php foreach($resultadodaBuscanoBanco as $resultado){ ?> <input type="text" name="txtnome" value="<?php echo resultado->login?>"required"> <?php} ?>OBS. without it shows the error of Trying to get property of non-object

Come on, Hugo!Well by the description I did not understand, but by its modeling and the domain of your project I think I can help you.MVC - There is a lot of confusion, many writers talking about time and end up confusing our head. The model concerns the business rules, this includes, the pojos that is the same thing that model, also includes the business that is where in fact should stay the business rules, calculations, DAOs etc. The view or View is literally the pages and does not necessarily remain in the application packages. Controller or controller is a role that can be played either by you or by the application server or by the framework you are using, this is the treatment of requests. Simple. But everyone creates an architecture in a way according to the understanding of these concepts.ORM mapping - By its domain (project) I found it a little confusing this data model (tables). But I would do this: create an Item entity with the id attributes, name, establishment and price. A Category entity with id, describing and other ItemsCompared with id, item, category.Thus you compare the items in a category and store in the table items compared according to the category. Did you understand?I hope I helped.

@@IDENTITY is used by SQL Server and not by MySQLpstmAux = conn.getConnection().prepareStatement("SELECT @@IDENTITY"); To recover the id from the logs entered in MySQL use LAST_INSERT_ID()pstmAux = conn.getConnection().prepareStatement("SELECT LAST_INSERT_ID()");

I will separate my answer in parts, answering your question: Yeah., it is possible to have more than one annotation @Id in its class, but, this is a facility that Hibernate provides and is not within the JPA specification.If you only use JPA, then this No will work.Now I'll explain how to make standard ways JPATalk is cheap, show me the code! - Linus TorvaldsUsing https://www.objectdb.com/api/java/jpa/IdClass This approach consists of creating a class containing the fields that form the identifiers of your entity, and referencing this class in the annotation @IdClass:public class ProjetoId { Long departamentoId; Long projetoId; } @Entity @IdClass(ProjetoId.class) public class Projeto { @Id private Long departamentoId; @Id private Long projetoId; ... } Using https://www.objectdb.com/api/java/jpa/EmbeddedId This approach consists of including a class that represents entity keys directly as a class attribute:@Embeddable public class ProjetoId { Long departamentoId; Long projetoId; } @Entity public class Projeto { @EmbeddedId private ProjetoId id; ... } This provides a good chance of reusing the code, as well as leaving the class cleaner.Using multiples @IdAs I mentioned before, this approach only works if you are using Hibernate, you can check the documentation by saying this http://docs.jboss.org/hibernate/core/3.6/reference/en-US/html_single/#d0e4819 , and I can also put the quote:5.1.2.1.2. Multiple id properties without identifier type Another, arguably more natural, approach is to place @Id on multiple properties of your entity. This approach is only supported by Hibernate (not JPA) compliant) but does not require an extra embeddable component.With this you can simply declare several ids:@Entity public class Projeto { @Id private Long departamentoId; @Id private Long projetoId; ... } I'll leave here too https://www.objectdb.com/java/jpa/entity/id to take a look.

Project patterns are also known as Design Patterns, so when you hear this term, you can be sure you will be referring to the same topic. The goal of design patterns or design patterns is to make reusable components that facilitate standardization, which allows agility for recurring problem solutions in system development. There are several types of project patterns currently, explaining what is each of them here would be very complicated, as it is a very long and comprehensive theme. I suggest you read this document. https://www.devmedia.com.br/entendendo-os-conceitos-dos-padroes-de-projetos-em-java/29083 DTO - Data Transfer Object is a standard of projects widely used in Java for data transportation between different components of a system, different instances or processes of a distributed system or different systems via serialization. The idea basically consists of grouping a set of attributes into a simple class to optimize communication. Ex: If you have a class with 50 attributes, and in a given job, you need to load only 3 of them. What to do? Thinking of improving the performance of the process, a DTO is created (which is nothing more than a common class), where you will receive the data of that class by passing only the 3 attributes you want to use. https://www.devmedia.com.br/diferenca-entre-os-patterns-po-pojo-bo-dto-e-vo/28162 Convert = Nothing more is than a class that will receive a random value and will convert the data of that object naturally. Usually used in projects JSF... When you work with SelectOneMenu (or SelectManyMenu) and entities in JSF occurs when we want the value of our SelectItem to be the entity itself, not the “id” of it. When you populate a type of object you usually have a reference to it in the “field” is an id, email, etc. Usually you want to work with it completely and not with pieces of it. Then the convert class converts this screen value to an entity type object. http://www.rponte.com.br/2008/07/26/entity-converters-pra-da-e-vender/ About Canonic Model I know very little, but take a cool article I found here on the net. https://sensedia.com/blog/soa/o-que-e-modelo-canonico/ Good Studies

Hello! The problem is in the logic you used. Your code is going through the list of registered clients, which is initially empty. How about that version? public static void CadastrarCliente(Cliente c) { foreach (Cliente ClienteCadastrado in clientes) { if (c.Cpf.Equals(ClienteCadastrado.Cpf)) { Console.WriteLine("CPF JÁ EXISTE NA BASE, CADASTRO RECUSADO."); return; } } clientes.Add(c); Console.WriteLine("CLIENTE CADASTRADO COM SUCESSO."); }