[英]SQL query select record with Max
我在下面有這些記錄:
CustomerID | Name | Store | Quantity
1 | Elie | HO | 16
1 | Elie | S1 | 4
我想僅通過提取最大數量來過濾客戶嗎? 我用Max嘗試過,但問題是我無法使用它渲染所有字段。 如果我在第一行中添加main.store,則會顯示第二行。 有什么解決辦法嗎?
Select main.CUSTOMER_ID, main.Name
from
(
Select Name = cus.FIRST_NAME + ' ' + cus.LAST_NAME,
Store = cs.NAME
,Transaction_Number = count(ts.TRANSACTION_SUMMARY_ID)
,cus.CUSTOMER_ID
from TRANSACTION_SUMMARY ts
inner join dbo.CUSTOMER cus
on ts.CUSTOMER_ID = cus.CUSTOMER_ID
inner join dbo.CORPORATE_STORE cs
on ts.CORPORATE_STORE_ID = cs.CORPORATE_STORE_ID
Group by cus.CUSTOMER_ID
,cus.FIRST_NAME
,cus.LAST_NAME
,cs.Name
) as main
Group by CUSTOMER_ID
,main.Name
order by main.CUSTOMER_ID
這是窗口函數的好用法:
with t as (
Select Name = cus.FIRST_NAME + ' ' + cus.LAST_NAME,
Store = cs.NAME,
Transaction_Number = count(ts.TRANSACTION_SUMMARY_ID) , cus.CUSTOMER_ID
from TRANSACTION_SUMMARY ts
inner join dbo.CUSTOMER cus on ts.CUSTOMER_ID = cus.CUSTOMER_ID
inner join dbo.CORPORATE_STORE cs on ts.CORPORATE_STORE_ID = cs.CORPORATE_STORE_ID
Group by cus.CUSTOMER_ID, cus.FIRST_NAME, cus.LAST_NAME, cs.Name
)
select name, store, Transaction_Number, CUSTOMER_ID
from (select t.*,
row_number() over (partition by customer_id order by transaction_number desc) as seqnum
from t
) t
where seqnum = 1;
您實際上可以免除子查詢。 但是,將窗口函數與聚合一起使用時乍看起來很有趣:
with t as (
Select Name = cus.FIRST_NAME + ' ' + cus.LAST_NAME,
Store = cs.NAME,
Transaction_Number = count(ts.TRANSACTION_SUMMARY_ID) , cus.CUSTOMER_ID,
row_number() over (partition by cus.CUSTOMER_ID
order by count(ts.TRANSACTION_SUMMARY_ID) desc
) as seqnum
from TRANSACTION_SUMMARY ts
inner join dbo.CUSTOMER cus on ts.CUSTOMER_ID = cus.CUSTOMER_ID
inner join dbo.CORPORATE_STORE cs on ts.CORPORATE_STORE_ID = cs.CORPORATE_STORE_ID
Group by cus.CUSTOMER_ID, cus.FIRST_NAME, cus.LAST_NAME, cs.Name
)
select name, store, Transaction_Number, CUSTOMER_ID
from t
where seqnum = 1;
請試試:
select * From tbl a
where a.Quantity=
(select MAX(b.Quantity) from tbl b where a.CustomerID=b.CustomerID)
你想要的是
select customer_id, max( quantity )
from main
group by customer_id
那么你可以使用它來加入自己
select *
from main
, (
select customer_id, max( quantity ) qty
from main
group by customer_id
) m
where main.customer_id = m.customer_id
and main.quantity = m.qty
顯然,此表中沒有name
,但您將其包括在內,所以我也這樣做了。
SELECT x.*
FROM my_table x
JOIN
( SELECT customerid
, name
, MAX(quantity) max_quantity
FROM my_table
GROUP
BY customerid
, name
) y
ON y.customerid = x.customerid
AND y.name = x.name
AND y.max_quantity = x.quantity;
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