I would have thought that by now business intelligence tools and Microsoft Excel would be happily coexisting. In some cases they are, but a larger number of Excel users, managers, and BI professionals simply seem battle weary.

This week at TDWI in Washington, DC, I taught an updated course on "BI & Excel: Friends or Foes?" I last taught this course four years ago. I learned my first lesson about BI and spreadsheets the hard way back in the early 1990s. At the time I was the project manager for a reporting system based on a custom transaction system. Typical of many IT projects, I gathered business-user requirements, went away for a couple months (at least it wasn't a year!), and we developed some parameterized reports on the mainframe.

The final solution was flexible, interactive, and exactly what the business users asked for. We launched the new reporting app in a training class I had personally developed and was thrilled to be teaching.

We were only half an hour into the class, when the power user in the group, Frank, declared, "I don't want any of this. I just want all my data in Excel."

Frank was the statistician in the group -- the trusted analyst. Normally, he and I were on the same side. We would swap notes on how to tweak Lotus macros or how to extract data from mainframe sources. But he basically just told me I had wasted months of effort and that what my team had built was crap.

The business managers in the room liked the reports, but they relied on Frank for all things data. Frank had planted a seed of doubt in their minds that our whole approach was wrong. Frank had become my foe. I tried not to get teary-eyed (hey, I was in my 20s!) and decided to cancel the rest of the class.

Frank felt fixed reports constrained him. He needed flexibility. For the managers in the group, who were not yet proficient in spreadsheets, the mainframe-based reporting system might have been fine. But Frank could make any data looking prettier in Excel, with better formatting, colors, charts, and so on.

Even though that lesson about the role of spreadsheets in BI was learned 20 years ago, BI leaders, managers, and Excel gurus continue to grapple with BI and Excel's coexistence.

At the start of this week's class, about a third of the attendees agreed with the suggestion that Excel and BI are friends; Excel helps improve decision-making and fulfills the vision for business intelligence. "I'm on the friend side because I know if I treat Excel as a foe, I will lose," said one attendee. "It's easier to embrace your enemy and gain trust and creditability."

The remaining two thirds felt that BI and Excel are foes: too many spreadmarts (some in the hundreds of megabytes) and multiple versions of the truth undermine the BI team's efforts to provide a single version of the truth. One attendee who started the day thinking spreadsheets were the enemy later said the class had changed her view.