我有一个如下所示的 SQL 查询:
select y.bid, format(((sum(y.loyalty_checks)/SUM(y.total_receipts_in_POS)) * 100),2) as Participation_Rate_or_percentage_loyalty_checkins from
(
SELECT receipt_stats.`business_id` as bid,
SUM(receipt_stats.total_receipts) AS total_receipts_in_POS,
c.loyalty_checks AS loyalty_checks
FROM receipt_stats
left JOIN
(
SELECT location_id as l, COUNT(checkins.`created_at`) AS loyalty_checks
FROM checkins
left join locations on locations.id = checkins.`location_id`
WHERE checkins.business_id = 570 and
DATE(receipt_date) BETWEEN '2016-01-01' and '2016-01-31'
AND checkins.STATUS = 'loyalty' and checkins.`approved` = 1
GROUP BY checkins.location_id
) c ON c.l = receipt_stats.location_id
where
date(receipt_stats.`receipt_date`) between '2016-01-01' and '2016-01-31'
and receipt_stats.`business_id` = 570
group by receipt_stats.`business_id`, receipt_stats.`location_id`
) y
我已经能够将查询的中间部分转换为 Rails 查询,如下所示:
def fetch_participation_rate(start_point,end_point)
receipt_stat_data = ReceiptStat.select("business_id", "SUM(receipt_stats.total_receipts) AS total_receipts_in_POS")
checkin = loyalty_checkins.select("location_id", "COUNT(checkins.`created_at`) AS loyalty_checks").where("DATE(receipt_date) BETWEEN ? and ?",start_point, end_point).
group("checkins.location_id")
stat = receipt_stat_data.select("c.loyalty_checks AS loyalty_checks").joins("left join (#{checkin.to_sql}) c ON c.location_id = receipt_stats.location_id")
stat = stat.where("date(receipt_stats.receipt_date) between ? and ?", start_point, end_point)
stat = stat.where("receipt_stats.business_id = ?", business.id)
stat = stat.group("receipt_stats.business_id, receipt_stats.location_id")
end
我卡住的唯一部分是 SQL 查询的第一行,即
select y.bid, format(((sum(y.loyalty_checks)/SUM(y.total_receipts_in_POS)) * 100),2) as Participation_Rate_or_percentage_loyalty_checkins from
最后一个
) y
请帮我解决这个问题。 谢谢。
最佳答案
使用 select
函数和 from
将此查询包装在外部 SELECT
/FROM
子句中:
def fetch_participation_rate(start_point,end_point)
receipt_stat_data = ReceiptStat.select("business_id", "SUM(receipt_stats.total_receipts) AS total_receipts_in_POS")
checkin = loyalty_checkins.select("location_id", "COUNT(checkins.`created_at`) AS loyalty_checks").where("DATE(receipt_date) BETWEEN ? and ?",start_point, end_point).
group("checkins.location_id")
stat = receipt_stat_data.select("c.loyalty_checks AS loyalty_checks").joins("left join (#{checkin.to_sql}) c ON c.location_id = receipt_stats.location_id")
stat = stat.where("date(receipt_stats.receipt_date) between ? and ?", start_point, end_point)
stat = stat.where("receipt_stats.business_id = ?", business.id)
stat = stat.group("receipt_stats.business_id, receipt_stats.location_id")
# Wrap our query in an outer query:
ReceiptStat.select("y.bid, format(((sum(y.loyalty_checks)/SUM(y.total_receipts_in_POS)) * 100),2) as Participation_Rate_or_percentage_loyalty_checkins").from(stat, :y)
end
请注意,第二个参数中的 :y
符号指定子查询的别名(在您的例子中为 y
)。
此外,虽然我无法直接根据您的代码检查这一点,但您可能会发现以下格式更具可读性:
def fetch_participation_rate(start_point, end_point)
checkin = loyalty_checkins
.select("location_id", "COUNT(checkins.`created_at`) AS loyalty_checks")
.where("DATE(receipt_date) BETWEEN ? AND ?", start_point, end_point)
.group("checkins.location_id")
stat = ReceiptStat.select("business_id, SUM(receipt_stats.total_receipts) AS total_receipts_in_POS, c.loyalty_checks AS loyalty_checks")
.joins("LEFT JOIN (#{checkin.to_sql}) c ON c.location_id = receipt_stats.location_id")
.where("DATE(receipt_stats.receipt_date) BETWEEN ? AND ?", start_point, end_point)
.where("receipt_stats.business_id = ?", business.id)
.group("receipt_stats.business_id, receipt_stats.location_id")
ReceiptStat
.select("y.bid, FORMAT((SUM(y.loyalty_checks)/SUM(y.total_receipts_in_POS) * 100), 2) AS Participation_Rate_or_percentage_loyalty_checkins")
.from(stat, :y)
end
关于mysql - 最后一步将 SQL 查询转换为 Rails Active Record 查询,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/37043136/