rules act like logical ors

or statement and join-or are a bit funky in how they work, and i haven't been very successful in using them

hmm, i can't seem to use missing? with fake data

i was trying to do some tests without making a DB, but i get errors with missing?

https://docs.datomic.com/on-prem/query/query.html#rules

you can combine rules to form ORs i think that is a good place to start.

I think you want something like this:

[:find ?fizz 
 :in $ ?my-date
 :where 
  [?fizz :fizz/buzz ?buzz]
  (or-join [?fizz]
    [(missing? $ ?fizz :fizz/date)]
    [(< ?my-date [?fizz :fizz/date])])]

@U0394DH0S3W Yeah that's what I meant, but the case is that this code do not work in datomic as this line gives me message:

[(< ?my-date [?fizz :fizz/date])]

While if I remove this one line it all works

https://docs.datomic.com/on-prem/query/query.html#predicate-expressions there is an example of using preds in a query

i'm not sure [?fizz :fizz/date] is valid. does anyone have examples of this syntax being used in queries?

[?fizz :fizz/date] is valid in a where, but I don’t think it does what you want. Sorry I didn’t pay too much attention to that when adding the or-join. [?fizz :fizz/date] unifies ?fizz to entities that have a :fizz/date attribute but it doesn’t extract the value of the attribute. I think this is what you want:

[:find ?fizz 
 :in $ ?my-date
 :where 
  [?fizz :fizz/buzz ?buzz]
  (or-join [?fizz]
    [(missing? $ ?fizz :fizz/date)]
    (and [?fizz :fizz/date ?fizz-date]
         [(< ?my-date ?fizz-date))])]