Some decisions IT professionals need to make are scary, and choosing database software is one of them. The stakes are high. If the sales database goes down, so do the sales reps, who can't access the leads, and the senior VP of sales, whose daily update of top customer concerns just stopped working. The customers getting database errors in their online payment histories are sunk as well. High stakes indeed.

Databases are big-ticket items for several reasons. The costs for these titans can spiral into six figures, they require specially trained database administrators (DBAs), and the software must often run on high-power server hardware that doesn't plug into a standard 110-volt wall socket.

Choosing where your most important business data will live means marrying into a database's strengths and weaknesses till death do you part. The resources that go into learning database languages, design, and client software make switching platforms as much fun as an across-the-board operating-system upgrade. When you can't fail and you can't switch, you have to be extra cautious, do careful research, and prototype your options before saying "I do."