From Sept 25, 2013: KTVU featured me speaking for OOW

On September 25, 2013, the American racing team led by Larry Ellison retook the America’s Cup in spectacular fashion, after several days and dramatic events.  Nobody could have predicted that the grand finish would end up happening in San Francisco Bay, within walking distance of Oracle Open World / JavaOne, and on the climactic “customer appreciation night” of that year’s conference.  It was an amazing once-in-a-lifetime event.

KTVU’s Jana Katsuyama featured me in a soundbite speaking on behalf of the very proud attendees of Oracle Open World, see below.

2013_09_25_Americas_Cup_OHearn_KTVU from Steve OHearn on Vimeo.

At first, Jana asked me a series of questions about whether attendees were upset that Larry’s attention was divided between the conference and the race, and that he’d missed a keynote earlier in the day to go celebrate the victory.

I said – no way! The conference is great, everything is well organized and continuing as planned, and who could possibly predict such a stunning situation – good for Larry!

And Jana, to her credit, let the spirit of my comments convey in the edited version that broadcast that evening on the leading Bay area news channel KTVU.

See above!

Rumors of SQL’s Death Have Been Greatly Exaggerated

The “NoSQL” revolution is tremendous on many levels.  It’s practical, relevant, and useful.  There are plenty of business situations where an architecture optimized for limited, targeted processing of very large amounts of data simply doesn’t need the overhead of a relational tool and can benefit from specialized functionality optimized for select purposes.

But SQL is still critical to the core operations of any enterprise.  Contrary to what many new-comers might think, “NoSQL” in a given application doesn’t actually mean “No SQL” across the board in the enterprise.  A lot of us who are responsible for enterprise architectures think of the expression “NoSQL” as really saying “Not Only SQL”.  After all – some NoSQL tools are actually built on a SQL platform. Believe it or not, the traditional relational database is still the number one technology for handling the mission critical core services of any professional organization.

However, this truth is apparently lost on some recent arrivals in the world of software development.

About a year ago I was invited to attend a conference in Maryland of one of the leading big data vendors.  Those of us attending were primarily software developers, and we all spoke in terms of various Apache open source projects and their commercial counterparts.  We rarely uttered the word “Java”, yet we were all Java developers of one kind or another.  And those of us in the world of Java development know better about the benefits and relative importance of both NoSQL and SQL platforms.

But I’m describing the attendees.  The conversation I’m about to share was with one of the vendors who was exhibiting at the conference.  (Yes, a commercial vendor was hosting a show at which they invited other commercial vendors, it happens all the time.)  He was trying to sell his company’s product, of course, a product that was complementary to the host company’s core offerings.  His company was one of those now-familiar business models where some developers created a cool open source project that they promoted to the Apache Software Foundation, eventually winning full project status.  With that established, the developers formed a company to begin selling support for the open source ASF product, and also began building a proprietary alternative for sale.  There are dozens of companies doing this nowadays, as we all know – and it’s a great business model, I love it.  More power to them.

So here I was chatting with a sales rep hawking his particular product.  Suddenly he declared the following:

“Well really, relational databases are dead, nobody uses those any more.”

I stopped.  The first visual that popped into my head was of that time as a kid when one of your friends tell you that “nobody” does this or “everybody” does that.  But as you get older, you learn that your fellow six year olds don’t necessarily have a handle on what the whole world is doing.

I’m sure this guy was a smart guy.  And his company was certainly offering a valuable product.  But some perspective was in order.

So I said – really? The RDBMS is dead?  Let me ask you some questions. Don’t you all sell this product?

Him: Yes.

Me: Well – don’t you track sales in a database? Orders, items, linked to the catalog? You probably track orders in an RDBMS.

Him: Well … ok, yes, probably.

Me: And the customers placing those orders? You need data about any number of contact methods, like phone numbers, email addresses, where to ship, when to call, etc., all connected to the orders, sales records, etc.  Probably all structured for mass mailings by correct categories at the right time. Sounds like an RDBMS. Right?

Him: OK, probably, yes.

Me: So … financial data? Employee info and HR compliance, other regulatory issues? Is that going to work in a NoSQL environment?

Him: Good point, probably not.

Me: So the RDBMS is tracking company orders, items, products, customers, employees, suppliers, accounting, finance, human resources, marketing contacts, contracts with events like this conference, and all other data associated with dollars, the law, whatever must be accurately tracked in line with the rest. Even online blog posts are probably running on an RDBMS, right? So that leaves, what, web log files and online comments for marketing trend analysis?

Him: Well no, more than that … but I see your point.

Me;  NoSQL has its place.  So does SQL.  Both are valuable.

Him: Agreed.

One down.

Lots more to go.

– Steve

P.S.  A huge thank you to Steve Feuerstein for encouraging this particular blog post, which is a direct result of a little exchange we had recently on this topic.  Thanks, Steve!

The latest happenings at the Baltimore Washington Java Meetup

I just sent out an email to the illustrious members of my Java User Group (JUG), aka the Baltimore Washington Java Meetup.  The text is below.  All those interested in Java technology are invited and welcome!

Well well well!  What an AMAZING night we had for our November meetup!  I’ve been remiss to have not sent this sooner – things have been busy busy busy in Steve world – but you should know that November 10th was an amazing night.  We had about a billion people there – well, ok, perhaps it wasn’t a billion, but in all seriousness we maxed out the room – and it was all to hear the most excellent presentation by our very own rock star, Markus Dale, and his Overview of Amazon Web Services (AWS) and its Java API.  On hand were many illustrious members of our meetup, plus some additional celebrities, namely AWS’s Walt Whitecotton, John Peterson, and John Quarentello, who brought plenty of Amazon swag with them as giveaways and door prizes.

Speaking of the door prizes … the questions were:

1) Do you use (circle all that apply) (a) Ant, (b)Maven, (c)Jenkins, (d) Hudson?

Every answer was selected and there was a write-in or two for Gradle. But the hands-down leading choice was Maven.

This question was posed at JavaOne to a room of about 200 developers.  By a show of hands, about half used Jenkins, half Maven, and two people use Ant.

2) An annotation can be extended: (a) True (b) False

The correct answer is false! Now … should they be extendable?  Well that’s a different question altogether.  But in the meantime –

Congratulations to all the winners, especially Peter Stamboulis who won the 1st place price, a gift card for Amazon Web Services!

Most of all, a great big thank you and “bravo!” to Markus Dale, who clearly knows his stuff and did a fantastic edge-of-your-seat presentation on one of the hottest cutting-edge topics in the IT field today.

SO … our next meetup is … TONIGHT!  As we’ve been saying this fall, our December meetup would be non-standard, not a technical session, and that’s definitely the case this evening! We are simply meeting for dinner at a great restaurant in Columbia – pay your own way – click here for details.

In 2016 we’ll resume with technical sessions and already have a few in the works:  Lambdas, data streams, new features in Java 9, our own participation in the Adopt-A-JSR effort, and more!

But for tonight, we’re having a fun holiday dinner (pay your own way!), and everyone is invited!

See you tonight!

– Steve

My SQL Expert Book and Practice Exams

I recently read in an online forum the online bonus exam for my book, OCA Oracle Database SQL Certified Expert Exam Guide (Exam 1Z0-047), is “no longer available” at the Oracle Press website.  I’m inquiring into this to determine if its true, and if so, to see if we can get it restored.  If you’ve had a similar experience, please email me to let me know.

In the meantime:

  • I have created additional practice exams here:  They are available at no charge, and only require that you registered an email address so you can take the exams in multiple login sessions if you wish.
  • I am currently working on a revision to my book, to upgrade it for Oracle 12c.  Lots of new feature we’re adding, and I’ll blog about those soon.  The second edition will be completed in early 2016.

In the meantime, if you’re looking for a practice exam, please check out!

Java, SQL, and the ORM Mismatch

I just can’t take it any more.

There is an incorrect perception floating around out there in Java world about the issue of mapping Java classes to SQL tables.  This issue falls within a larger topic often referred to as the object-relational mapping (ORM) mismatch.  This “mismatch” is based on the fact that Java is object-oriented, and SQL is not, so using Java classes to represent SQL tables involves some issues, and requires some clever work.  That is true.  But it’s led to a major misperception about SQL being supposedly “defective”.  It is not, but this notion has crept its way into two books I’ve read lately, books by otherwise very smart people, published by major cutting edge IT book publishers.

(For the record, no, neither publisher in question is my own publisher, the incomparable McGraw-Hill Education and their awesome imprint with Oracle Corporation, Oracle Press.)

I’m not going to verbally quote either work, but the idea goes like this:

  • To support persistence (storing data), you map a Java class (ex., “Customer”) to a corresponding SQL table (ex., “CUSTOMERS”)
  • When creating two Java classes, it’s possible to design them with a many-to-many relationship to each other
  • SQL doesn’t support the creation of tables with many-to-many relationships
  • Therefore SQL is defective.

Uh – no.

Folks, the presence of a many-to-many relationship in your data model is a sign that you aren’t finished with your data model.

This isn’t a Java thing, or a SQL thing, it’s a real world thing.

It’s possible to build a defective data model in Java.  You can do a lot of stupid stuff in Java.  You can also build bad data models in SQL, and technically you actually can create a many-to-many in SQL, but it won’t work.  That’s a good thing.  I’ll explain shortly with an example.

But first, a word about the classic mismatch.


The authors of these two books I’ve read are Java developers first and foremost.  I get that, and I know where they’re coming from.  I’m a Java developer myself, and have been since Java was first introduced into the Oracle database as an alternative to PL/SQL, which I also love – so much that my first book was the official Oracle Press certification exam guide OCP Developer PL/SQL Program Units Exam Guide.

But about the time that book hit the shelves, I began working with Java, which had become available as an in-database alternative to PL/SQL.  I soon thereafter began teaching Java.  In fact, this is me with then-CEO of Sun Microsystems, on the first day I launched my first ever course in Java:

Scott McNealy, Steve O'Hearn, at the National Press Club

That was taken at the National Press Club.  McNealy was hysterically funny that day and a great guy. He’s responsible for, and oversaw, a lot of great developments in Silicon valley that reverberate to this day – like Java.

And back at that time, the first question about Java was – how do we get Java and SQL to interact?  That, after all, was Oracle’s whole point of embedding Java in the database.

Java has come a long, long way since then, and all for the better.  There is a well established and growing library of packages and tools for implementing various interactions between Java and SQL.  And at the heart of them all is often the same issue:

Java is object oriented, and SQL isn’t.

True.  So what?  Newcomers to Java act like this is some kind of ultimate nightmare scenario, a sign that SQL is out of sync with the world.  Nonsense.  SQL isn’t inherently object-oriented, but neither is your file system.  And yet Java interacts with files just fine.  Now granted, the idea behind SQL is more sophisticated than file systems.  But on the other hand, SQL isn’t in the same category as a third-generation language (3GL) like Java, SQL is a fourth generation language (4GL). It might not support object-oriented dynamics, but neither does it clash with them.  This is demonstrably obvious – otherwise we wouldn’t have JDBC, the Java Persistence API (JPA), and Hibernate.  So the two can and do work together, and effectively.  But it takes a bit of work; SQL doesn’t necessarily provide built-in support for all object-oriented concepts, such as inheritance. (Caveat: Inheritance actually can be supported in data modeling – see this article – and there’s a way to do it within SQL itself, sort of, but as to whether it’s helpful or not, that’s a different story, and perhaps the topic of a future blog post.  Or book.  Hm …. )

Frankly, when I hear about the “mismatch” between Java and SQL, I think of the issue of transactions, that’s the only real issue to me. The object life cycle and nature of Java is such that it introduces challenges in the way persistence to the database is best done in a multi-user/multi-threaded environment.

But let’s get back to topic and dispel this “SQL is defective” myth.


Data modeling is the act of representing real world business processes through diagrams of the things (“entities”) that comprise a real world process, and the relationships (or “associations”) among those entities.  The most obvious entities are easy to identify – customers, products, office buildings, vendors, cars, etc.  But the more abstract entities are not always so obvious – work schedules, change orders, reservations, that sort of thing.  This is where the importance of understanding many-to-many relationships can be very helpful.


I’m going to use an example taken from the airline industry, as I’ve been meeting lately with Lisa Ray, a lifelong aviation data expert closely involved with a series of legacy migrations in that area. (And for the record, she fully gets this.)

Let’s start with two obvious entities:

  • Planes – as in “individual planes”, not just types of planes.
  • Pilots – individual people.

Every one plane might be flown by more than one pilot.  Every one pilot will be qualified to fly more than one plane.  Sounds like a many-to-many relationship, right?  And as you might know, an entity-relationship diagram illustrates the “many” side of a relationship with the classic crow’s-feet line:

ERD Diagram A

So that’s our initial logical diagram for these two entities.

Now folks, this blog post is not going to be a complete tutorial on how to perform data modeling, but we will explore one key aspect of modeling: whenever you encounter a many-to-many relationship, you ALWAYS transform it using the following steps:

  • Add a third entity in between – “Entity_3” in our diagram below.
  • Create foreign keys within the new entity for the primary keys of the existing entities – in this case, PLANE_ID as a foreign key to the PLANES entity’s PLANE_ID primary key, and PILOT_ID as a foreign key to the PILOTS entity’s PILOT_ID primary key.
  • Establish “one-to-many” relationships between the new entity and the existing entities, using the “single-line” to indicate the “1” side, and the “crow’s foot” to indicate “many” side of the relationship.

Like this:

ERD Diagram B

The reason we do that is simple:  the presence of a many-to-many relationship is a clear indicator that something else goes in between the two entities.  The question is not “if” something belongs there.  Something does belong there.  The only question is – what exactly is it?

In our example, it’s going to be something like a “roster”, or a “schedule”, or “flight assignments”, or “rentals”:

ERD Diagram C
Call it what you will, but something goes in between and it must be included in your data model.  That new entity will have its own attributes.  Perhaps:

  • A start and end date to the time of assignment
  • A name of a key staff member authorized to approve the assignment

Who knows what might be there? But something is there, and the presence of the many-to-many relationship is your clue to its existence.

That third entity is often a bit more abstract.  You can see pilots and planes, but a “flight assignment” isn’t necessarily as obvious.  But it’s an important entity in the data model nonetheless.

One more point:  this third entity isn’t some necessary crutch to get around a “SQL defect”. I can’t believe what I’ve read in certain Java books that suggest such a thing.  No.  This third entity is a real world “thing” that definitely exists in order to enable the relationship with the real world, and it’s up to you to identify it. Whether you figure it out or not, it exists nonetheless.

The rule is simple: no complete data model exists with any “many-to-many” relationships.  If such are present, you aren’t done modeling yet.

So now that you understand this, imagine reading a Java manual in which someone explains that SQL is “defective” because it “doesn’t support many-to-many relationships”.


Now you know!

O’Hearn is the Java leader of the only officially recognized JUG for the DC metro area.  He is also the author of the first-ever expert-level certification exam guide from Oracle Press, titled OCA Oracle Database SQL Certified Expert Exam Guide (Exam 1Z0-047).  The 2nd edition of his SQL Expert book, revised for Oracle 12c, is due out in 2016.