sql - Count records which has no association or association of association meets condition -
assume have 3 classes:
class person belongs_to :group end class group has_many :people has_many :tags end class tag belongs_to :group end
it possible, person
may have group_id = null
.
what need, count person
records has group_id = null
or group
doesn't have tag
record attribute status in ('active', 'finished')
one more thing, has fast possible. querying on milions of records.
ideas? thanks.
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