module Arel module Predications def eq_or_null(other) left = eq(other) right = eq(nil) left.or(right) end def not_eq_or_null(other) left = not_eq(other) right = eq(nil) left.or(right) end def gteq_or_null(other) left = gteq(other) right = eq(nil) left.or(right) end def lt_or_null(other) left = lt(other) right = eq(nil) left.or(right) end def in_or_null(other) left = self.in(other) right = eq(nil)