Question

鉴于以下模型：

class PeriodBilling < ActiveRecord::Base

  belongs_to :appcode
  belongs_to :period
  belongs_to :sla
  belongs_to :unit_type
  belongs_to :dpc_employee
  belongs_to :general_ledger

end

class GeneralLedger < ActiveRecord::Base

  has_many :appcodes
  has_many :sla_task_details
  belongs_to :expense_category
  has_many :period_billings
  has_many :expected_billings


end

如何在Rails中找到以下SQL等效项，以显示为左侧为句点的矩阵和顶部的general_ledgers，并在相应的字段中添加总和（pb.current_amt）？

select pb.pe_number, gl.general_ledger_number, sum(pb.current_amt)
from period_billings pb, general_ledgers gl
where pb.sla_id = 21
and pb.general_ledger_id = gl.id
group by pb.pe_number, gl.general_ledger_number

在Active Record中，这是我想要找到的东西：

@sla = Sla.find(params[:id])
@period_billings = PeriodBilling.where("sla_id = ?", @sla.id).group_by(&:general_ledger_id)
@billing_sum = @period_billings.inject(0){|sum,billing| sum+billing.current_amt}

所以，我想找到所选sla的所有period_billings，按general_ledger_id分组，得到这些记录的period_billing.current_amt的总和。然后，我想将12个时段放在一边，以在顶部的相应general_ledger列中显示总计金额。

提前致谢!!! ：）

Answer 1

对我建议的事情只是一个疯狂的小刺。有些东西更适合直接sql，当出现这种情况时，就像你要求的那样，最好只使用sql。

ActiveRecord::Base.connection.execute <<-EOF
select pb.pe_number, gl.general_ledger_number, sum(pb.current_amt)
from period_billings pb, general_ledgers gl
where pb.sla_id = 21
and pb.general_ledger_id = gl.id
group by pb.pe_number, gl.general_ledger_number
EOF

Rails相当于SQL

1 个答案: