Question

我有一个名为loan_emi的表。我想选择最后一个emi支付日期，最后一个emi日期，总数没有。 emi，没有。付费的emi和没有。无偿的emi。这是我的询问。

SELECT MAX(emi_date)AS pay_date,
  (SELECT MAX(emi_date) FROM loan_emi WHERE l_id=a.l_id AND is_paid=0
  )AS last_date,
  (SELECT COUNT(id) FROM loan_emi WHERE l_id=a.l_id
  )AS tenor,
  (SELECT COUNT(id) FROM loan_emi WHERE l_id=a.l_id AND is_paid=1
  )AS paid,
  (SELECT COUNT(id) FROM loan_emi WHERE l_id=a.l_id AND is_paid=0
  )AS unpaid
FROM loan_emi a
WHERE id   =" + lId + "
AND is_paid=1 GROUP BY l_id

但这是多个子查询。请帮我简化一下。提前谢谢。

Answer 1

只需为每个字段添加一个case / when的单个查询。这样，对于所讨论的ID的所有记录，没有连接，没有子查询，它是一次传递。另外，正如我所说的那样，您可能希望PARAMETERIZE您的查询指明相关帐户的ID ...

SELECT
      MAX( case when is_paid = 1 then emi_date else null end ) as Pay_Date,
      MAX( case when is_paid = 0 then emi_date else null end ) as Last_Date,
      COUNT(*) as Tenor,
      SUM( case when is_paid = 1 then 1 else 0 end ) as Paid,
      SUM( case when is_paid = 0 then 1 else 0 end ) as Unpaid
   from
      loan_emi
   where
      id = ?ParameterizeYourIncomingID
   group by
      l_id

简化多个子查询

1 个答案: