The first question here isn't the usual "why?", it is "how?".
How did he open them both at the same time? - He had network access to the database host from his development machine, and credentials to the production database saved in his client or easily available.
What could discipline do here? Even if he didn't intentionally connect to the production database during his development hours, it could still be in "recent connections" of his DB editor tool, so he could accidentally open only that one someday, in the only tab.
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The first question here isn't the usual "why?", it is "how?".
How did he open them both at the same time? - He had network access to the database host from his development machine, and credentials to the production database saved in his client or easily available.
What could discipline do here? Even if he didn't intentionally connect to the production database during his development hours, it could still be in "recent connections" of his DB editor tool, so he could accidentally open only that one someday, in the only tab.