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[英]SQL alternative for fetching latest record of each item in a table using partition
[英]SQL to fetch Latest record of each item from the table
我試圖查詢數據庫以使用max(Created_at)
並按stockId
分組獲取每只股票的最新記錄,但它會帶來每個項目的第一個id
及其最后一個Created_at
。
我怎樣才能讓它集體帶來最新的記錄? 請幫忙。 我的查詢如下:
SELECT a.id as A_id, b.id as B_id, max(b.Created_at) AS Created_at
FROM beta b
INNER JOIN alpha a ON b.a_id = a.id
GROUP BY a.id
您可以使用諸如ROW_NUMBER()
類的分析函數:
SELECT A_id, B_id , Created_at
FROM
(
SELECT a.id as A_id, b.id as B_id , b.Created_at,
ROW_NUMBER() OVER (PARTITION BY a.id ORDER BY b.Created_at DESC) as rn
FROM beta b
JOIN alpha a ON b.a_id = a.id
) q
WHERE rn = 1
您的記錄按 stockID( a.id
) 分組,並在按created_at
列降序排序后選擇最新的記錄。 如果關系(每個分組stockId
均等created_at
值)很重要並且所有令人滿意的結果都應包含在結果集中,則將ROW_NUMBER()
替換為DENSE_RANK()
。
據我所知,你需要這樣
declare @item table
(
itemid int
,itemname varchar(100)
)
insert into @item
values(1,'A'),(2,'B'),(3,'C')
declare @stock table
(
itemid int
,stockid int
,updatedate datetime
)
insert into @stock
values(1,1,'2020-08-04 13:11'),(1,1,'2020-08-04 14:11')
,(1,2,'2020-08-04 15:11'),(1,2,'2020-08-04 14:11')
select * from @item a
inner join
(select stockid,itemid,max(updatedate)lastupdatedate from @stock
group by stockid,itemid
)b on a.itemid=b.itemid
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