June 2010
Intermediate to advanced
328 pages
7h 51m
English
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How to Recognize the Antipattern
The problems with using ENUM or a check constraint arise when the set of values is not fixed. If you’re considering using ENUM, first ask yourself whether the set of values are expected to change or even whether they might change. If so, it’s probably not a good time to employ an ENUM.
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“We have to take the database offline so we can add a new choice in one of our application’s menus. It should take no more than thirty minutes, if all goes well.”
This is a sign that a set of values is baked into the definition of a column. You should never need to interrupt service for a change like this.
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“The status column can have one of the following values. We should not need to revise this list.”
Shouldn’t need to ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.