In my 15+ years of web development, there are very few things I can say are unequivocally a good idea. It almost always does depend. Storing timestamps instead of booleans, however, is one of those things I can go out on a limb and say it doesn’t really depend all that much. You might as well timestamp it. There are pl...
Ehhh, I don’t quite agree with this. I’ve done the same thing where I used a timestamp field to replace a boolean. However, they are technically not the same thing. In databases, boolean fields can be nullable so you actually have 3-valued boolean logic:
true,false, andnull. You can technically only replace a non-nullable field to a timestamp column because you are treatingnullin timestamp asfalse.Two examples:
A table of generated documents for employees to sign. There’s a field where they need to agree to something, but it’s optional. You want to differentiate between employees who agreed, employees who disagreed, and employees who have yet to agree. You can’t change the column from
is_agreedtoagreed_at.Adding a boolean column to an existing table. These columns need to either default to an value (which is fair) or be nullable.
Using a nullable Boolean to represent 3 distinct states just adds confusion and complexity to your system. In most cases I would prefer to use an enum with 3 fields which is non nullable.
Completely agree, I cram a timestamp column in every table, but booleans have their purpose too.
Yeah, this feels like “premature optimization”. When you design your applications and databases, it should reflect your understanding of the problem and how you solved it as best as possible. Using
DATETIMEOFFSET NULLwhen you actually meanBIT NOT NULLisn’t saying what you mean. If you already understand that you have a boolean option and you think you might need a timestamp to track it, use 2 columns. Or an audit table. So sayeth the holy SRP.