This is an interesting question that I sometimes find myself thinking about. I’ll start with my answer, I actually don’t know, but I can show you that all them can be!
Since my wife is doing a Ph.D. in biology she reads and analyzes a lot of data and also decides how to present it (or criticizes how others present theirs). So it got me thinking about the way to present the most common database in the world. Note that I’m not even talking about getting the data and its correctness, only the way to analyze it.
When people ask me “which is the most common database” I ask them back: “which is the most common language in the world?” and then ask “Why?”. In this case you can present the data differently, and it all depends on how you declare “common”. When talking about common languages, I often get the answer “Chinese” (or Mandarin), and this is correct, assuming you count the number of people that speak that language as native speakers. However, I can count the most common language as “the language that is spoken in the largest number of countries in the world (as a first-language)”. This is a little bit harder to find on the internet, but it should be Spanish. Another way to define “common language” is “How many people in the world speak this language (generally, not as native speakers), and this is probably English (though I couldn’t find a reliable source for that). And these are not the only ways I can think of to define a “common language”.
With databases it’s even more complex, and it’s more difficult to get the correct data. When someone asks me about the “most common” database, I guess I can give them several databases as an answer, and I won’t be wrong. I guess this is exactly what the marketing departments of these companies do.
The most “common database” can be:
- The one with the largest number of installations
- The one with the largest number of installations when only counting production
- The one with the largest number of installations, but only in certain organizations (enterprises for example)
- The one that holds the largest total amount of data (how you measure data will be the key here, raw data only? Do you count duplicates?)
- The one that the largest number of organizations use (count only the number of organizations, not the databases)
And these are only 5 options, I can think of some more very easily…
So I guess we can find definitions for the most “common database” that will suit SQL Server, Oracle, MySQL, DB2 and more as answers.
Another problem in our case, as I mentioned above, is that we don’t have all the data.The companies won’t provide this information, and even if they do, there is no way to verify it. With the free databases it’s even more difficult, as we don’t actually know when someone installs it and uses it.
So, the next time someone tells you they are the most common database in the world, ask yourself if they tell you how they measure it.