Range Query

2 August, 2024

So, at one moment i think what of kind of query the range query is? It turn out just yet another fancy name and don't over thinking ot it ever again. This is the principle.

Range query is for when the clause is not an equal (=).

Or, in more generic sense: Range query is for whatever that could return more than one exact result.

SQL:

select * from users where id>1;
select * from users where created_at between '2024-08-01' and '2024-08-02';

Datalog:

(d/q '[:find ?e
       :in $ n
       :where
       [?e :user/id ?x]
       [(> ?x n)]
       ]
     (d/db (:qln.pnr/datalevin-conn qln.sys/*sys*))
     1)

(d/q '[:find ?e
       :in $ dt1 dt2
       :where
       [?e :user/id]
       [?e :user/createdAt ?x]
       [(> ?x dt1)]
       [(< ?x dt2)]
       ]
     (d/db (:qln.pnr/datalevin-conn qln.sys/*sys*))
     (java.util.Date/from (java.time.Instant/parse "2024-08-01T00:00:00Z"))
     (java.util.Date/from (java.time.Instant/parse "2024-08-02T00:00:00Z")))