[英]How to get a negative rownumber in sql server
我有一組帶有DateTime
的數據,比如說CalculatedOn
我想要的是從當前日期getdate()
開始,並獲得當前日期之前的x
量記錄,以及之后的相同數量。
如果x = 50
那么現在前50,現在前50。 我當時認為rownumber()
對於這個來說是完美的,但是我想不出如何將前面的行數為負數而將來為正數。
還有一個問題是,如果沒有50個先前或將來會發生什么,但那將會發生。
假設該表只有兩列:
create table MyTable
(
Id int not null constraint pk_mytable primary key,
SomeTextIWant nvarchar(50) not null,
CalculateDate DateTime not null
);
結果:
如果今天是25/04 12:54
然后
Id, SomeTextIWant, CalculatedDate
-- 50 from before now--
-----now here-----
-- 50 from after now--
如果你想在之前和之后獲得50行,也許這會做你想要的:
with cte1 as (
select top 50 t.*
from table t
where CalculatedDate <= getdate()
order by CalculatedDate desc
),
cte2 as (
select top 50 t.*
from table t
where CalculatedDate > getdate()
order by CalculatedDate
)
select *
from (select * from cte1 union all select * from cte2) t
編輯:
從問題的上下文中我不清楚是否確實需要行號。 很容易添加,thoug:
(select top 50 t.*,
- row_number() over (order by CalculatedDate desc) as rownumber
from table t
where CalculatedDate <= getdate()
order by CalculatedDate desc
)
union all
(select top 50 t.*,
row_number() over (order by CalculatedDate) as rownumber
from table t
where CalculatedDate > getdate()
order by CalculatedDate
)
您實際上可以將這些組合成一個查詢:
select t.*,
((case when CalculatedDate < getdate() then -1 else 1 end) *
(row_number() over (partition by (case when CalculatedDate < getdate() then 1 else 0 end)
order by (case when CalculatedDate < getdate() then CalculatedDate end) desc,
CalculatedDate asc
)
)) as rn
from table t;
您可以將其放在子查詢中並選擇-50到50之間的rn
。
但是,我不確定如何處理第0行,並且該問題沒有提供有關如何處理與getdate()
匹配的任何記錄的信息(盡管不太可能)。 我認為第一個答案是OP需要的。
您可以使用兩個CTE,一個用於過去,一個用於將來的日期,然后將ROW_NUMBER
與ASC
和DESC
,在此之前乘以-1
並連接所有:
WITH dataBefore AS
(
SELECT d.*, rn = (-1) * row_Number() over (Order By CalculatedOn DESC)
FROM dbo.TableName d
WHERE CalculatedOn < GetDate()
)
, dataAfter AS
(
SELECT d.*, rn = row_Number() over (Order By CalculatedOn ASC)
FROM dbo.TableName d
WHERE CalculatedOn >= GetDate()
)
SELECT * FROM
(
SELECT db.*
FROM dataBefore db
UNION ALL
SELECT da.*
FROM dataAfter da
)x
WHERE x.rn >= -50 AND x.RN <= 50
ORDER BY x.RN
試試這個...
With myCte
As
(
Select top 2 column1,column2 from YourTable where yourdate > '2014-04-23'
union
Select top 2 column1,column2 from YourTable where yourdate < '2014-04-23'
) select ROW_NUMBER() over (order by column1) as RNO,* from myCte
使用RowNumber
SELECT TOP 50 ROW_NUMBER() OVER (ORDER BY CalculateDate) AS RowNum,
id, SomeTextIWant, CalculateDate
FROM MyTable
WHERE CalculateDate > @Date
UNION ALL
SELECT TOP 50 -ROW_NUMBER() OVER (ORDER BY CalculateDate DESC) AS RowNum,
id, SomeTextIWant, CalculateDate
FROM MyTable
WHERE CalculateDate < @Date
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