[英]Convert an SQL query to Rails Active Record query last step
我有一個SQL查詢,如下所示:
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
我已經能夠將查詢的中間部分轉換為Rails查詢,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
我遇到的唯一部分是SQL查詢的第一行,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
和最后一個
) y
請幫我解決這個問題。 謝謝。
使用select
函數和from
將此查詢包裝在外部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
請注意,第二個參數中的:y
符號指定子查詢的別名(在您的情況下為y
)。
此外,雖然我無法直接對您的代碼進行檢查,但您可能會發現以下格式更具可讀性:
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
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