best way to store this data in the database

I tend these days to always use the full descriptive words - memory
implications are small, but it is easier to directly display the value
than have code to expand it wherever it is used. It also tends to
make the code logic easier to follow.

tonypm

I tend these days to always use the full descriptive words -

Definitely not in a case like this. The set of three values here maps
*perfectly* to SQL-style 3-valued logic -- so use it! Store this as a
boolean value.

A larger set of strings could be stored directly in a character field
in the database, but if the number is under 100 or so, I'd advise
creating a separate table and simply referring to the strings by
foreign key. This practice will avoid all sorts of data normalization
issues. I'd never dream of storing a small number of repeating
strings as literal text the way you're suggesting.

memory
implications are small, but it is easier to directly display the value
than have code to expand it wherever it is used.

Not really -- especially if the application should run in more than
one language.

It also tends to
make the code logic easier to follow.

Again, not really. You have to explicitly test for == 'yes' rather
than simply testing for truth or falsehood.

tonypm

Best,