How to Program with Java Podcast

Cascading Style Sheets are a bit of a tricky beast in HTML. Given this fact, I wanted to dedicate an entire section to just this topic. Let's start with the basics, shall we? What are Cascading Style Sheets (CSS)? Well, we've already talked a little bit about HTML formatting tags (like  ), but that kind of formatting is embedded within your HTML code itself. What I mean by that is while you are ty...

In this HTML tutorial I would like to introduce two concepts to you: DOCTYPE Styles The DOCTYPE Currently as of the date this was published, web browsers are (mostly) supporting HTML 5. HTML has gone through several versions and variations over it's lifetime, and because of this it's highly suggested that you include something called a DOCTYPE. The purpose of a DOCTYPE is to tell the web browsers...

I'm so ridiculously excited to be introducing a whole new aspect of programming. Over the next few months I will be posting new articles on the topics of HTML, Javascript and jQuery. These are all technologies that you can use to create your very own interactive website. The really cool thing about building websites, is that you can leverage your existing knowledge of Java to create ever MORE powe...

The presentation layer is one of the three main layers in object-oriented programming. The three main layers include: Presentation Layer Business Layer Data Layer Now, these three layers are typically related to enterprise web applications. It's a design pattern used to help separate your code out in three distinct areas that (if need be) can easily be switched out with another programming languag...

In our last Hibernate lesson, you learned  how to fix duplicate data from hibernate queries . In this lesson we're going to focus on some of the aggregate functions  that can be used with Hibernate, and of course that means diving into the Group By  clause. What's important to note is that Hibernate doesn't ever refer to it as  group by , instead they use the term  projections . So, armed with thi...

How to Fix Duplicate Data from Hibernate Queries This problem was the bane of my existence when I first started using Hibernate because I had no idea where the problem was coming from. If you're executing a query and finding that you have a bunch of duplicate records and haven't a clue why, then you're in the right place. You see the problem is typically caused by having left joins (or optional jo...

Now it's time to dive into the nitty gritty of Hibernate's mysterious inner workings. I'm by no means an expert in Hibernate, but I do use it almost every day for my own projects, so I do know a thing or two about how it works. One topic that had me scratching my head for ages was the Hibernate life cycle. What I mean by the life cycle is the way Hibernate interacts with Java objects at certain po...

What the heck is a Fetch Type? Great question! Hibernate is a very handy framework for removing your need to fully understand SQL, but it will force you to understand things such as  joins . Joining two tables in SQL is the foundation of a relational database, as joins allow you to actually define relationships between tables (objects). Having said that,  relationships  are important to understand...

Hibernate @ManyToMany Unidirectional The Many-to-Many relationship can be best described by example. The example we're going to use is that of the relationship between an  Author  and a  Book . Author s publish  Book s, and  Book s have  Author s. Any one  Author  can publish many  Book s, and any one  Book  can be published by many  Author s, so this is why it is a many to many relationship. Othe...

One-to-One Unidirectional Relationship Since you've already learned about the ins and outs of how  unidirectional one-to-many  and  bidirectional one-to-many  relationships work, it's time to learn about the One-to-One relationships. We will start things off with the unidirectional One-to-One relationship and how it's set up in Hibernate. First thing is first, you need to understand  how a One-to-...

Since we've already learned about the unidirectional @ManyToOne relationship, we can now move on to talking about what a bidirectional relationship is like, when using Hibernate. The term "bidirectional" literally means "functioning in two directions", which is the concept that we will apply in our relationships between two Java objects. When we have a bidirectional relationship between objects, i...

In the past we have learned about database relationships, specifically the  One-to-Many  as well as the  Many-to-Many and One-to-One  and that was all good, great and grand… But now I want to talk about how to create those same relationships inside of Hibernate. Specifically, I want to focus on the One-to-Many relationship in Hibernate and how we go about mapping it out in our Java objects. But be...

Data Access Objects – What are they? Data Access Objects (or DAOs for short) are used as a direct line of connection and communication with our database. DAOs are used when the actual CRUD (CRUD = Create, Read, Update, Delete) operations are needed and invoked in our Java code. These data access objects also represent the "data layer" of our application. These objects are still just plain old Java...

What You'll Learn The focus of this podcast / blog post is to teach you how to create the connection between your Java objects and the SQL Database tables. Remember, the whole point of the Hibernate framework is for you to be able to write Java code that allows you to communicate with your database. When I say that the goal is to communicate with your database, what I mean is: Create the tables (i...

What is a Persistence Framework? As the name implies, it has something to do with persisting things... this means that we're still talking about databases.  But what is it that we are persisting with this framework? Objects (of course) A persistence framework is something we use in Java to bridge the gap between Java and SQL. Hopefully we've gone through all of my previous tutorials and have learn...

The SQL Subquery Now that you've learned about  SQL Joins ,  aggregate functions and the  group by keyword , it's time we moved on to our final topic in our SQL tutorial series. Today you'll be learning all about SQL Subqueries, how to use them and when you should use a SQL subquery. So, what is a subquery? First and foremost, let's get the jargon out of the way. A subquery can also be referred to...

After having talked about all the  SQL Aggregate functions , there's one more topic that goes hand in hand with what we've already learned… The  group by  keyword. This particular keyword allows us to take a bunch of data and mash it all together into matching groups and then perform aggregate functions on those groups (like  sum  and  avg ). You might ask yourself why you'd want to "mash together...

In today's podcast episode you'll be learning all about the aggregate functions that exist in SQL. What the heck is an aggregate function? Well that's what I'm going to try and teach you today, and I promise, it's not a difficult concept to grasp. Just think of an aggregate function as a method that you're calling that will process data in your database and return a value. Obviously the returned v...

There are three categories of joins that you can make use of in SQL:   Inner Join   Outer Join   Cross Join   But before we dive into the categories of joins, we first need to have an understanding of what a join really is. Joins are used in SQL to bring together all the relevant data from multiple database tables.  Remember that we've broken data down into multiple tables and established relation...

In this SQL tutorial episode/post we're going to learn how to enforce our SQL relationships that we've already learned about. We're going to be tackling the one-to-one and many-to-many relationships and we're going to learn how to write the code to enforce these relationships in our database. As outlined in the podcast, we are going to be focusing on the many-to-many relationship with the  author...

You've learned all about how to create sql queries to read, write, update and delete data… but you haven't yet learned how to create the tables where you'll be doing the reading, writing, updating and deleting. So that's what today's podcast is all about, be sure to click the play button above this to listen to the show and then follow along with the notes via http://howtoprogramwithjava.com/sessi...

Show Notes available via : http://howtoprogramwithjava.com/session43   In this post we will be expanding on the topic of database relationships and touch on two that are less common but just as useful. Many-to-Many Relationship The many-to-many database relationship is used when you are in the situation where the rows in the first table can map to multiple rows in the second table… and those rows...

We've talked about relational databases already, and we've learned why this type of database management really dovetails with the object oriented programming model. So now I want to dive into the specifics when it comes to relationships. What are the different types of relationships in SQL? There are three types of relationships you can have in SQL, they are: One-to-Many One-to-One Many-to-Many In...

Terminology It's the foundation when learning any new concepts.  In this episode of the "How to Program with Java Podcast" we will be talking about some new database terminology. One of the most important aspects of modern databases is the fact that they allow you to define relationships. Relationships between tables allow you to break data up into its individual "areas of interest".  But when you...

What's all this CRUD about? C reate R ead U pdate D elete This is the at the heart of all databases and SQL. A database essentially carries out these four operations over and over again for the duration of its existence. In this podcast, I talk about these four database operations in detail and the actual syntax that is used in a flavour of SQL known as MySQL.