获取行取决于内部连接导轨范围

Question

I have the following scope:

scope :billable, -> (range_start = nil, range_end = nil) {
    joins(:bids)
      .where("auctions.complete = 1 AND auctions.starts_at >= ? AND auctions.starts_at <= ? AND auctions.listing = 0", range_start, range_end)
      .group("auctions.id")
  }

I am trying to determine how to add a constrain to the where clause that allows me to select where count(bids) > auctions.items_count

Answer 1

See http://guides.rubyonrails.org/active_record_querying.html#having

Thing to keep in mind in SQL:

• The WHERE clause is for conditions on individual rows, before they have been put into groups by a GROUP BY.
• The HAVING clause is for conditions on groups.

You have a condition on which groups to include in the result, since your condition uses the aggregate function count() . So it belongs in the HAVING clause.