Balancing Work and Life

Balancing work and home life is nothing new; we’ve had this challenge for a long time. But in recent months when so many companies are streamlining operations and asking their employees to do more with less, the challenge has gotten noticeably more difficult. I recently interviewed someone who had struggled with this in a mighty way; he’d worked more weekends than not during the past twelve months and had reached a point of burn out.

In addition to the direct work requirements of our jobs, there are also the quasi-work activities of blogging, attending user group meetings, learning new technologies, and volunteering in the community. All of these are good activities, but they take time. And that time has to come from some where.


In Cheaper by the Dozen, Steve Martin’s character, Coach Tom Baker, faces this dilemma when his boss, Shake McGuire, demands more time from the Coach despite the pressures at home. Shake is surprised when Tom Baker resigns from his dream job. Tom Baker summarizes his rationale very succinctly. “If I screw up raising my kids. nothing I achieve will matter much.”

Priorities matter. Balancing work and home matters.

So how can we better balance our work life and home life? I suspect you already know the answer to that question. It’s the doing of the answer that’s difficult.

Tips For Balancing

  • Realize That You’ll Never Get Everything Done. I’m a doer. I like checking items off a to-do list. But I’ve learned that my to-do list will never reach zero. There will always be something else to do. I will not be able to finish everything before I go home for the day. Once I made peace with that, some of the self-imposed stress that accompanies open items and drives me stay late at work begins to melt away.
  • Place Your Family Events On The Calendar. I learned a long time ago that if an event is not on my calender, it will not happen. I’m too busy to remember everything that is important to me. So I put family events on my calendar. Boy Scout events? On the calendar. My daughter’s piano recital? On the calendar. You can mark them private if you wish, but staking the claim on the calendar will prevent others from scheduling meetings during important family events.
  • Learn To Say “No”. This is one of my biggest challenges. I want to help with each request that comes to me. And considered in isolation, it’s easy to think that it’ll only take a small amount of time. But all of those little items add up. Learning to say No at work, at home, and at volunteer events will help to add some much needed margin to your life.
  • Make Up Your Mind Ahead Of Time. As Socrates once said “the life which is unexamined is not worth living.” Take the time to know what is important to you before you are put in a situation that challenges you. If I’m asked to attend a SQLSaturday when I have a family commitment, I won’t go. Family is important to me.
  • Time Box Your Activities. I can write a magazine article in four hours or it can take four days. It all depends on how much time I allow. Parkinson’s Law states that “Work expands so as to fill the time available for its completion.” Perfectionists are really susceptible to Parkinson’s Law. Time boxing is the practice of allocating a set amount of time for an activity. When you reach the end of the time, you’re done. This prevents you from revising and revising again and wasting time with only marginal gains in the output (aka the Law of Diminishing Returns).

Beware Of Too Many Good Things.

The challenge in putting these ideas into practice is that most of the time, the things that we are doing are good things. Speaking at conferences, staying late to go the extra mile for a client, teaching a Sunday School Class, leading a Boy Scout troop, are all good things. And all have their place. But too many of them too often can lead to problems.

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SQLPeople: An Interview With Andy Leonard

The thing that I most enjoy about going to conferences, SQLSaturdays, and user group meetings is the people I get to meet or see there. That’s why I was intrigued when SQLPeople was announced a few months ago.

Recently I had an opportunity to spend time with Andy Leonard (twiter | blog) when he came to Nashville to deliver SSIS training for a client. I truly enjoyed the afternoon we spent savoring hot beverages on the porch of a local coffee shop.

More recently I talked with Andy about SQLPeople. Here’s what he had to say.

JW: Tell me a little about yourself, Andy.

AL: I’m a believer, husband, dad, and grandfather; a farmer, author, and blogger; a SQL Server database developer and SSIS architect. I’m an engineer at heart and I’ve been honored to be a SQL Server MVP for four years.

JW: Professionally speaking, how do you spend your day?

AL: Tweeting. Seriously, I schedule many tweets about a week (or more) in advance – especially the stuff announcing blog posts and Andy Leonard Training, Inc. courses. My days are divided between billable work, business development, and community activities.

JW: You’re known as one of the top SSIS people in the world. How did you get started?

AL: I think there are lots of really smart SSIS people in the community – plus me! I was fortunate enough to be working for Brian Knight when writing began on the Professional SSIS 2005 Wrox book. Brian found himself needing authors and was kind enough to give me an opportunity to work on the project.

JW: How did you learn SSIS?

AL: When we started working on that book, the only people that knew anything about SSIS were the developers building it. They put out Channel 9 videos and blog posts and we gobbled them up while the bits were still warm. I also built relationships with members of the SSIS team at Microsoft. Folks like Donald Farmer, Matt Masson, Ashvini Sharma, and Kirk Haselden were very patient and transparent with me as I bugged them via email. Donald and Matt remain patient with me as I continue to learn. As you know, the SQL Server Community is awesome. I continue to learn SSIS from Jamie Thomson, Adam Machanic, Brett Flippen, Rob Farley, Todd McDermid, John Welch, Jessica Moss, Rafael Salas, Julie Smith, and many others (too many to name!).

JW: How has the SQL community helped you in your career?

AL: Gosh, I wouldn’t have a career without the SQL Server Community. Or I would, but I can’t imagine it would be this cool. I first interacted with the Community via books and newsgroups (remember newsgroups?). I was in a temp-to-perm position (still a temp) trying to get my first big data warehouse to perform when I ran across a post from Kalen Delaney about the impact of Where clause field order in VLDB tables. Everything else I’d read talked about selectivity and density, and I’d tried just about everything to get this one query to perform. Since the reporting tool generated T-SQL semantically, the Where clause was always ordered the same way – which just-so-happened to be the inverse selective/dense order! I took Kalen’s advice and the warehouse started returning results. I got to meet Kalen and Ken Henderson at the PASS Summit 2004 (“The Year of the Storms”). I went into that conference suffering from a serious case of Imposter’s Fear – I kept thinking “someone is going to figure out any day now that I don’t know what the heck I’m doing. Then I’ll get fired.” I left the Summit thinking “I’m a database professional.” That was the beginning of what the SQL Community has done for me.

JW: What is SQLPeople?

AL: That’s a good question! I have an evolving blub posted on the About page. SQLPeople is more defined by what it’s not than what it is, so I’ll start there. SQLPeople is not a bureaucracy. There’s no hierarchy, administrative staff, or leadership in the sense of a board; rather Brian Moran and I bounce ideas around and implement the stuff that survives our strategic thinking email chains. Right now, SQLPeople is a series of interviews to help the SQL Community get to know each other better. Some of the people interviewed are recognizable industry names. Some are not, or at least not yet! I’m learning things about our peers right along with everyone else. I find each interview fascinating and really appreciate the support from the SQL Community. There’s also an upcoming SQLPeople Event in Richmond Virginia 9 Apr. Brian and I have a few ideas worked out that we’ll be announcing this Spring, and we’re always thinking about cool new ways to serve the Community. We believe the key to Community is serving others. Hence the name: SQLPeople – people are first.

JW: How did you come up with the idea for SQLPeople?

AL: Ok, this is weird but true: I had a dream. In the dream I was sitting on a stage interviewing someone and there was this banner hanging from the front part of the stage with the SQLPeople logo. I woke up – it was around 4:00 AM – went to my office and used Word to capture that logo from the dream. I saved it and went back to bed. When I woke up a few hours later, I honestly thought I’d dreamed the whole thing – getting up and everything. But when I checked Recent Items I found SQLPeople.docx. The idea for interviews and SQLPeople Events started there. Serving the Community is something I’ve enjoyed doing for a long time. I hope to continue.

JW: Who is currently involved?

AL: Brian Moran and I are shepherding the vision. Chuck Boyce is working with us on media ideas. Everyone contributes to “visioneering.” We seek – and take – advice from lots of people in Community leadership. We listen, we do not discriminate, and attribute anything we use.

JW: You’ve been involved in other SQL communities. How is this one different?

AL: The “flatness” of it all is very appealing. You don’t have to be elected to be heard (and receive a response / attribution), bureaucracy is non-existent; this combines to allow more focus on serving individuals and the Community. Preserving the “brand” is often a consideration for organizations (as it should be). We preserve the SQLPeople brand by serving people – first.

JW: Are there different aspects to SQLPeople?

AL: Yep. There are the Interviews, of course. There’s the SQLPeople Person of the Year. There’s SQLPeople Events. And there’s more to come – look for an announcement in April and another in the September timeframe. And that’s just the stuff we’ve thought of so far!

JW: What’s the main emphasis of the group? Networking, education, community, something else?

AL: Inspiration is at the top of the list. We believe the items you list flow from inspiration. I know a lot of database professionals. I’ve taught a lot of folks SSIS, and I’ve learned the number one issue isn’t that people don’t know SSIS; it’s that they don’t know what’s possible. With all the information available online, if I can show you something is doable, you can figure out a way to do it. If, while showing you it’s possible, I can inspire you so that you want to do it – there’s no stopping you. Networking, education, and community are very important and all of them have a place in SQLPeople’s endeavors. But they all start with Inspiration.

JW: Tell me about the inaugural SQLPeople event.

AL: It’s in Richmond Virginia on 9 Apr 2011. Scheduled speakers include Michael Coles, Gray Proulx, Jeremiah Peschka, Kendra Little, Brian Moran, and Scott Currie. The format is a 20-minute presentation followed by a 20-minute interview (by me) with questions from floor. We’ll do two speaker sessions/interviews followed by a networking session of 30-minutes; rinse and repeat. Chuck’s recording everything and the goal is to host the videos at Folks can learn more and sign up at the website </ShamelessPlug>.

JW: If you could accomplish only two things with SQLPeople in the next 24 months, what would it be?

AL: Wow, that’s a good question. My first wish is for two more wishes! Seriously, though… The SQL Community is huge and growing. First, I hope SQLPeople refocuses the global conversation in the SQL Server Community on serving individuals and our community. My personal motto is: I am Here to Help™. I see that reflected in SQLPeople already. There’s too much fear, self-preservation – and frankly, selfishness – demonstrated in the recent actions of organizations within our community. Watching it has been personally wrenching. I understand the logic behind the tragic decisions, made even more so by allowing (insisting, even) that people serve process instead of the other way around. SQLPeople isn’t against anyone or any organization. SQLPeople is for people. Second, I’d like to facilitate ideas, projects, and events that inspire database professionals while remaining what Umair Haque describes as a Meaning Organization. As such, we think about significance, outcomes, harmony, purpose, peace, love, and ambition.

JW: What’s your long-term vision for SQLPeople?

AL: Long-term specific goals are really fuzzy at this time. Brian and I have put a lot of thinking into framework-type strategy (the aforementioned Meaning Organization, for example) and thought experiments. We’re in the “what if?” business. Patterns are emerging. Sometimes we bring templates to the table from experience – things that have worked well and things that have not. Sometimes the patterns emerge organically and we grab our boards and start surfing. SQLPeople has less vision than you’d expect from an idea focused on bring inspiration, but it has a purpose. And that purpose is to serve the SQL Community.

JW: What about the project makes you really excited?

AL: I sound like a broken record: Serving the SQL Server Community is really exciting stuff! There are so many ideas out there – so many visions – that need a little initiative applied. I haven’t mentioned this previously: the writings of Seth Godin serve as a pretty cool source of execution ideas. As do the writings of Andy Warren and some guy named Joe Webb. The thing about executing visions is it requires work, trust, and respect. I’ve seen volunteer organizations struggle with this – inside and outside of the SQL Server Community. Rather than try to collect all the initiative under a large umbrella called SQLPeople, we’re hoping to inspire and facilitate folks with good ideas. Brian and I have no illusions: the potential of SQLPeople lies not with us – it lies with the Community, with the people.

JW: How can others participate in the project?

AL: I tried to think of everybody when I sent out the interview questions, but I left out a bunch of cool and interesting people! If you’d like to be interviewed for SQLPeople, please email me ( Folks are welcome to read and comment on the interviews and coming-soon content on the website. For people interested in attending, the SQLPeople Event in Richmond should be a blast. Also, our announcements scheduled for April and September 2011 will provide more ways for (SQL)people to join in the fun.

I really appreciate the time that Andy dedicated to this interview. He’s a quality guy. If you have an opportunity to spend some time with him, don’t pass it up. You won’t regret it.

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The Three C’s Of Interviewing

A client of mine recently asked me to help fill a junior-level position in their organization. This isn’t uncommon; I regularly help clients interview and select qualified IT Professionals to join their ranks.

Usually I’m usually given a detailed job description with very specific requirements. The manager frequently believes that the requirements for the position are very unique, very specific to the organization.

Sometimes this is true; often it is not.

As a result of this perceived uniqueness of the position, many hiring managers mistakenly settle for the first person that meets their minimum requirements. Sometimes, they even settle for less than their stated minimum.

This is unfortunate. It is a disservice to their organization, to the ill-fitting candidate that’s hired, and to the other candidates who would have been a better fit in the organization. The organization has to suffer through a lackluster performer. The person hired is put into a role where he has little chance for success. And other, potentially really qualified, candidates loose out on a great opportunity.

Past Performance Is No Guarantee Of Future Success

When I interview candidates for a position, I ask questions that help me to gauge their likelihood for success. Predicting success is not easy; it’s a difficult undertaking. But trying is important for the obvious reasons.

Much has been written about interviewing techniques and asking good questions so I won’t go into a lot of details on this subject.

I will say, however, that I like scenario-based questions. These kinds of questions reveal quite a bit about how a person approaches his job.

What are some scenario-based questions?

  • “Tell me about a time when you and the development team didn’t see eye to eye on an issue and how you handled it.”
  • “Describe a time when the budget you were given was far less than needed and how you adapted to the new limitations.”
  • Think back to a time when one of your projects was at risk of missing a deadline. How did you approach the problem and what did you do?

Although these kinds of questions will not guarantee that you’ll find the rose among thorns, they do offer some insight into the candidate’s experience and outlook.

What To Look For When Interviewing A Candidate

As I interview candidates, I’m look for what I call The Three C’s of Interviewing. Before I recommend a candidate for hire, I want to make sure that both the client and I are comfortable in the following three areas.

  • Competency. Does the candidate have a good base onto which to build? No one is likely to meet every single requirement. And even if he did, he’d still have to learn the specifics of this environment. So it’s important that he has a good foundation on which to build, that he can learn quickly, and that he sees opportunities not obstacles.
  • Compatibility. Will the person be a good fit with organization? Can he get along with the others? Perhaps the role requires a significant amount of individual work without the input of others. Can he work alone? Or can he function as a member of a larger team if required?
  • Core Values. Is the person trustworthy? Does he have a good work ethic? Do I believe that he will take ownership of issues? Will he work hard? Is he a go-getter, or does he lack initiative? Can I trust that he can and will do what he says that he’ll do?

These are the qualities that I look for in a candidate. Yes, experience with specific tools and technologies is important. But don’t overlook the the intangibles of the Three C’s.

Question: What do you look for when you interview candidates for an open position in your organization?

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An Outpouring From The Twitter Community

Last week, I was in Redmond, Washington, for the Microsoft MVP Global Summit. This was my fourth time attending the Summit; it’s a great opportunity for networking and providing feedback to Microsoft about their products.

I love catching up with people that I only see once or twice a year.

A Change Of Plans

I arrived late Sunday evening. Monday and Tuesday were packed with technical sessions and energizing keynotes. I learned a lot about the direction Microsoft is considering for future versions of their products.

Everything that’s discussed at the Summit is covered under a Non-Disclosure Agreement (NDA). I cannot even share the names of the sessions or the speakers who presented. But it was good stuff. I learned quite a bit and hopefully provided some insightful feedback to the product teams.

I was expecting to spend Wednesday, my final day at the summit, doing more of the same. I had signed up to attend sessions on particular technology that I haven’t used much.

But that all changed with a text from my wife telling me that my six-month old was sick; she was taking him to the doctor. An hour later, another text arrived saying that the doctor was sending them to the Emergency Room!

I Gotta Go!

I had to get home. So I packed my stuff and called a cab to take me from the Microsoft campus to my hotel room and then on to the airport.

I also called the airline to rebook a flight for that day. The average wait time was 37 to 51 minutes! I wanted to be on a plane in that time frame, not waiting on hold.

I headed to the airport anyway, without a reservation.

An Outpouring Of Community

As I was doing these things, I shared my trials with the Twitterverse. I tweeted that I need to leave early to be with my wife and six-month old at the hospital.

The well-wishes came pouring in from my Twitter friends. Prayers were offered. Help was offered. Words of comfort were expressed.

A couple of friends searched the web for airline flights to get me home that afternoon.

Another friend shared a premier services telephone number for the airline.

Several friends offered to be the single point of contact for me during my travels, providing me with their cellphone numbers.

One friend even offered to have a meal delivered to my home to help make sure the older four kids had something to eat while my wife and I were occupied with the little one.

I was amazed at the support that came pouring in through my Twitter feed.

A very special thank you to each of you who shared the burdens with me that day and in the days that followed. There are far too many to name specifically or individually, but you know who you are. And please know that I truly appreciate it, more than you know.

David spent three days in the hospital with RSV, a viral infection in the lungs. Thankfully, he’s home now and has fully recovered.

What is Twitter?

Some people say that Twitter is a complete waste of time, that it’s idle water-cooler chat that distracts from real work. It can be.

Others say that it’s a great way for businesses to promote and protect their brand. It can be that too.

But to me, Twitter offers people a chance for community. In a time when the world is getting smaller and faster, Twitter is community. People can interact and invest in each others lives in a way like never before. Does it replace the local community? No, not even close. But it can extend your reach and broaden your community.

So, my Twitter friends, I’m going to have a barn-raising soon. Any takers?

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Writing Better Queries Presentation Materials

I delivered a webcast for the PASS DBA Virtual Chapter yesterday. It was called Tips & Tricks for Writing Better Queries. I really appreciated everyone who made the time to attend. I hope you found it to be time well spent.

As promised, here is a copy of the slide deck and demonstration code I used during the session. Please let me know if you have any questions.

The presentation was recorded and should be available on the PASS web site within a few days.

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How To Write Better Queries WebCast

One character. That’s all it takes; just one character in a Transact-SQL query can make the difference between an index seek and an index scan.

Transact-SQL is easy to learn. But to truly get the best performance from your SQL Server you must have a good understanding beyond the basics of syntax. To become a Transact-SQL Superhero, you must be aware of some of the nuances of the language and how little things can affect your queries.

PASS DBA Virtual Chapter LiveMeeting Event

On Wednesday, 23 February, 2011, at noon Eastern Standard Time, I’ll share some of the lessons I’ve learned during my years of working with SQL Server. We’ll discuss indexing, stored procedures, triggers, and even user-defined functions.

I hope you’ll join me for this free webcast.

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How Should the PASS Nominating Committee Be Selected?

Over the past few months, the Elections Review Committee (ERC) has been looking into how the community should select its future leaders in the PASS organization. We started with a clean slate. Nothing in the existing process was considered sacred or off-limits. Nothing was considered out of scope. We want to find the best possible way for the community to be completely engaged in the process.

After a great deal of well-reasoned discussion and deliberation, we’ve decided that there does indeed need to be a way to effectively narrow down the field of potential candidates. There are simply too many problems and risks associated with having an unbounded number of candidates on the slate. The issues range from not have enough voters to effectively decide the election, to having ill-equipped candidates reaching the Board, to having competing organizations stuffing the ballot boxes.

This means that some body should exist to consider the applications and pare them down to a more manageable number from which the community can choose. For the sake of continuity, we’ll call this body the Nominating Committee (NomCom).

We’re still discussing how the NomCom will do its job. Expect another post on that topic later.

Who Should Be On The NomCom?

One of the questions that the we’ve grappled with is: how should the members of the NomCom be chosen? If the Board hand selects the NomCom, then they can effectively control the election by controlling who serves on the NomCom.

On the other hand, each NomCom member should have an intimate awareness of PASS, its needs, its operation, etc. Without an understanding of the organization, how can a committee select the most qualified individuals?

So, we’ve put together a draft of the process we’re considering recommending to the Board. This is not finalized. We’re putting it out to the community and we want your feedback.

To see the proposed process, visit the ERC web site. Read the proposal and give us some feedback. We want to make this better.

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The Importance Of Managing Expectations

Have you ever taken a sip of sweet tea only to discover that it was soda instead? Eeww! What an eye-opening experience!

Don’t misunderstand; I like soda. But when I’m expecting sweet tea, the normally pleasant taste of the carbonated beverage is face-wrenchingly awful.

Thus, the importance of expectations.

What To Expect?

When working with your clients, your boss, your spouse, your kids, and everyone else for that matter, it’s critically important to set expectations. Let them know what to expect. Let them know when to expect it. Let them know any caveats that may exist. It gives them a sense of comfort.

As with the beverage example, expectations are important; the same result can be interpreted as good or bad depending on expectations.

If you promise a client that you’ll provide a deliverable in ten business days and you deliver it in seven, they’re very happy. Conversely, if you promise to deliver in five and you don’t have it ready until the seventh day, they’re disappointed. In both cases they receive the deliverable in seven days, yet in one case you’re a hero and in the other case you’ve failed.

How Can You Manage Expectations?

Managing expectations is not difficult. In fact, it’s straightforward.

  • Under Promise. Don’t over commit yourself. Examine your workload, your capabilities, your own expectations, and then build in some margin.
  • Over Deliver. This go right along with Under Promise. Going the extra mile and exceeding expectations is a nice way to give them a sense of “wow”.
  • Communicate Clearly. It’s been said that there are four components to communication: the sender, the message, the medium, and the recipient. A breakdown and any of those can lead to a misunderstanding. Make sure that the message that you intend to deliver is the one that is received.
  • Communicate Frequently. Providing timely updates about the progress along the way is just as important as setting the initial expectations. Any delays, any changes to the initial expectations should be communicated early in the process.
  • Be Honest. As the old saying goes, honesty is the best policy. Best honest with others. If you are unsure of the outcome, tell them. It’s better that they know this up front.

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Book Review: The Lazy Project Manager

“There is nothing more uncommon than common sense.” Some attribute the axiom to Frank Lloyd Wright but others are adamant that he’s not the origin of it. Whoever said it had a somewhat elitist or cynical perspective about the general population.

At times, however, the saying has proven itself to be true. That’s why sometimes it’s best to state the obvious, rather than taking it for granted.

In his book “The Lazy Project Manager“, Peter Taylor doesn’t tackle the basics of Project Management as a profession. Do don’t buy the book as a Project Management how-to guide; it’s not intended to be that. Taylor rightly observes that much has already been written on the topic. He even provides list of resources that he’s found helpful in the back of “The Lazy Project Manager”.

Instead Taylor attempts to supplement the purely academic studies of Project Management with practical and actionable approaches.

A Common Sense Approach

“The Lazy Project Manager” focuses on the subtle nuances of how to shepherd a project from its initial phase through to its completion. Taylor concentrates on working with your team to move the project toward success. He advocates using humor to diffuse a situation, evaluating the team personnel, and remembering that communications is more than just the message.

Much of what he shares should be considered common sense, especially to a seasoned professional. However, the advice proffered will likely be helpful to many who are new to the project manager role.

This short book is replete with anecdotes from Taylor’s experiences. He shares some of his successes as well as his miscues over the years. He recounts his missteps and what he’d do differently now that he’s on the other side of the mishaps.

Proper Planning

Despite the intentionally eye-catching title, the book’s premise can be distilled down to the old adage of the 7 P’s: Proper Planning and Preparation Prevents Pitifully Poor Performance.

Taylor contends that most projects require an awful lot of work up front and if done well, the long middle part of the project goes very smoothly. Eventually every project wraps up with a flurry of concluding activities at the end.

The book models this as well. The first portion of the book sets the stage. Then Taylor offers to let the reader skip the middle section and just right to the end of the book where the final two chapters summarize everything that you may have skipped.


I suspect many who buy the book can easily skip to end without missing anything; I certainly felt as though I could have. Others may find the middle, though it sometimes wanders a bit, to be helpful.

The eight reviewers on Amazon give the book a 4.5 out of 5 stars. I think that’s a bit on the high side. I’d give it a 3 to 3.5 out of 5 stars. But then, I’ve been self-employed 15+ years and I’ve managed hundreds if not thousands of projects.

Whenever there is a hard job to be done I assign it to a lazy man; he is sure to find an easy way of doing it. – Walter Chrysler

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A NULL Is Not Unknown

Like it or not, NULLs happen. I don’t think that’s I’ve ever seen a production database that didn’t have NULLs.

Waiter, there's a NULL in my soup.

I’m not arguing whether or not NULLs in a database are good or bad. That discussion ranks up there with religion, politics, and naming conventions. My point is that NULLs exist. They are a fact of life and we must understand them conceptually before we can handle them programmatically.

So, What Is A NULL Anyway?

Let’s start with a definition. NULL is a convenient way to represent the absence of a value. It is not zero in the case of numeric columns. It is not a zero-length string in character columns. It is most assuredly not 1900-01-01 in a date column.

A NULL means that no value has been supplied. There is no value. There is no string; there is no number; there is no date. There is only the absence of a value.

But Doesn’t NULL Mean An Unknown Value?

It’s true that we don’t have an actual value for NULL. But that doesn’t necessarily mean the value is “unknown”. Let me illustrate with an example.

Consider a web site where pet owners make appointments with a Pet Cosmetologist. (I know; just go with it.) The web site asks the pet’s name, species, etc. One of the questions is the pet’s gender. For some animals, this is a very straightforward question. For other animals, answering that question takes uncommon skill.

The web developers recognized that some pet owners may not know Puddle’s gender so they provided three options in the drop down list: Male, Female, and Unknown. That should handle most every case. Dog owners can enter Male or Female as appropriate. Owners of kittens can enter Unknown.

I'm just not myself without a mani-pedi.

Gender is not a required field on the web site. The owners of the Pet Boutique don’t want to turn away an appointment request just because the pet’s owner doesn’t answer a question. Thus, owners of kittens who are embarrassed by their sexing ineptitude can leave that answer blank.

See the difference? When the pet owner enters Male or Female, we know the gender of the animal. If they enter Unknown, we have a value provided by the owner. We don’t know whether to expect a boy or girl, but we have been given an answer to the question.

If the non-required question is left blank, we may end up with a NULL in the database. So NULL is the absence of a value altogether. It’s a question unanswered. Of course, the web developers may default to “Unknown” but that, in itself, may be misleading since it was not provided by the user.

Next Up: Nullology 101

If NULLs permeate our databases, it’s critical that we understand their affect. For example:

  • What happens when we sum a column that contains NULLs?
  • What happens if we concatenate strings that contain NULLs?
  • Can a NULL equal another NULL?

I’ll tackle these questions and more in the next post.

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