class ConceptQL::Operators::TrimDateStart
Trims the start_date of the LHS set of results by the RHS's latest end_date (per person) If a the RHS contains an end_date that comes after the LHS's end_date that LHS result is completely discarded.
If there is no RHS result for an LHS result, the LHS result is passed thru unaffected.
If the RHS result's end_date is earlier than the LHS start_date, the LHS result is passed thru unaffected.
Public Instance Methods
query(db)
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# File lib/conceptql/operators/trim_date_start.rb, line 34 def query(db) grouped_right = db.from(right_stream(db)).select_group(:person_id).select_append(Sequel.as(Sequel.function(:max, :end_date), :end_date)) where_criteria = Sequel.expr { l__end_date >= r__end_date } where_criteria = where_criteria.|(r__end_date: nil) # If the RHS's min start date is less than the LHS start date, # the entire LHS date range is truncated, which implies the row itself # is ineligible to pass thru ds = db.from(left_stream(db)) .join(Sequel.as(grouped_right, :r), l__person_id: :r__person_id) .where(where_criteria) .select(*new_columns) .select_append(Sequel.as(Sequel.function(:greatest, :l__start_date, :r__end_date), :start_date)) ds = add_option_conditions(ds) ds.from_self end
Private Instance Methods
new_columns()
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# File lib/conceptql/operators/trim_date_start.rb, line 59 def new_columns (dynamic_columns - [:start_date]).map { |col| "l__#{col}".to_sym } end
occurrences_column()
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# File lib/conceptql/operators/trim_date_start.rb, line 55 def occurrences_column :end_date end