[英]LEFT JOIN with multiple nested select
以下語句出人意料地起作用,但是我不確定3次加入同一張表是否有效。 我必須禁用ONLY_FULL_GROUP_BY
才能使其正常運行。
有2張桌子在玩。 一個是包含Distributor信息的主表,第二個是包含主表(assoc)中關聯的Distributor的amount
, date
和id
的購買表。
我需要三件事。 年初至今的銷售額,該總額表示某個分銷商從當年起的銷售額。 去年的銷售額,與上一年相同。 然后,最后只需獲取最新的購買日期和金額即可。
用戶需要能夠按這些值( lys
, ytd
等)進行過濾,因此將它們作為變量連接似乎是一種方法。 數據庫大小約為7,000條記錄。
SELECT
d.*,
ytd_total,
lys_total,
last_amount,
last_purchase
FROM Distributor as d
LEFT JOIN (
SELECT
assoc, SUM(amount) ytd_total
FROM purchases
WHERE db = 1 AND purchase_date >= '{$year}-01-01'
GROUP BY assoc
) AS ytd
ON ytd.assoc = d.id
LEFT JOIN (
SELECT
assoc, SUM(amount) lys_total
FROM purchases
WHERE db = 1 AND purchase_date BETWEEN '{$lyear}-01-01' AND '{$lyear}-12-31'
GROUP BY assoc
) AS lys
ON lys.assoc = d.id
LEFT JOIN (
SELECT
assoc, amount last_amount, purchase_date last_purchase
FROM purchases
WHERE db = 1
GROUP BY assoc
) AS lst
ON lst.assoc = d.id
WHERE ........
您可以在每個聚合查詢中做更多的工作。 我認為這更是您想要的:
select d.*, pa.ytd_total, pa.lys_total, pa.last_purchase_date, p.amount
from distributor d left join
(select p.assoc,
sum(case when p.purchase_date >= '{$year}-01-01' then p.amount end) as ytd_total,
sum(case when p.purchase_date BETWEEN '{$lyear}-01-01' AND '{$lyear}-12-31' then p.amount end) as lys_total,
max(p.purchase_date) as last_purchase_date
from purchases p
where p.db = 1
group by p.assoc
) pa left join
purchases p
on pa.assoc = p.assoc and pa.last_purchase_date = p.purchase_date;
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