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比方說,我有以下Datomic模式:查找:db/txInstant與Datomic中的屬性中定義的日期最接近?
; --- e1
{:db/id #db/id[:db.part/db]
:db/ident :e1/guid
:db/unique :db.unique/identity
:db/valueType :db.type/string
:db/cardinality :db.cardinality/one
:db.install/_attribute :db.part/db}
{:db/id #db/id[:db.part/db]
:db/ident :e1/createdAt
:db/valueType :db.type/instant
:db/cardinality :db.cardinality/one
:db.install/_attribute :db.part/db}
{:db/id #db/id[:db.part/db]
:db/ident :e1/e2s
:db/valueType :db.type/ref
:db/cardinality :db.cardinality/many
:db.install/_attribute :db.part/db}
..
; --- e2
{:db/id #db/id[:db.part/db]
:db/ident :e2/guid
:db/valueType :db.type/string
:db/cardinality :db.cardinality/one
:db/unique :db.unique/identity
:db.install/_attribute :db.part/db}
{:db/id #db/id[:db.part/db]
:db/ident :e2/startedAt
:db/valueType :db.type/instant
:db/cardinality :db.cardinality/one
:db.install/_attribute :db.part/db}
{:db/id #db/id[:db.part/db]
:db/ident :e2/stoppedAt
:db/valueType :db.type/instant
:db/cardinality :db.cardinality/one
:db.install/_attribute :db.part/db}
..
我想找到E1 或作出與E1相關聯的任何E2的最後交易:db/txInstant
其中,e1的:e1/createdAt
或E2的:e2/startedAt
或:e2/stoppedAt
小於或等於供應日期(#inst
)。我如何在Datomic中構建這樣的查詢?
這幾乎是我之後我,但我想2016-10 -26給我實體的最新db/txInstant而不是「nothing」。還可以調整查詢來適應這種情況嗎? – Johan