Sql 从同一表中具有最早值的表中选择ID的不同列表
我有下表Sql 从同一表中具有最早值的表中选择ID的不同列表,sql,sql-server,greatest-n-per-group,Sql,Sql Server,Greatest N Per Group,我有下表 SDate Id Balance 2016-01-01 ABC 3 2016-01-01 DEF 7 2016-01-01 GHI 2 2016-02-01 ABC 6 2016-02-01 DEF 4 2016-02-01 GHI 8 2016-02-01 XYZ 12 我需要编写一个查询,为我提供一个日期范围内Id的不同列表
SDate Id Balance
2016-01-01 ABC 3
2016-01-01 DEF 7
2016-01-01 GHI 2
2016-02-01 ABC 6
2016-02-01 DEF 4
2016-02-01 GHI 8
2016-02-01 XYZ 12
我需要编写一个查询,为我提供一个日期范围内Id的不同列表(因此,在本例中,
SDate>='2016-01-01'
和SDate您可以使用一个派生表来完成此操作,该派生表首先计算出每个Id
值的最小SDate
值。然后使用该派生表将连接到原始表,以找到与这些值匹配的行的余额
:
declare @t table(SDate date,Id nvarchar(3),Balance int);
insert into @t values ('2016-01-01','ABC',3),('2016-01-01','DEF',7),('2016-01-01','GHI',2),('2016-02-01','ABC',6),('2016-02-01','DEF',4),('2016-02-01','GHI',8),('2016-02-01','XYZ',12);
declare @StartDate date = '20160101';
declare @EndDate date = '20160201';
with d as
(
select Id
,min(SDate) as MinSDate
from @t
where SDate between @StartDate and @EndDate
group by id
)
select d.Id
,t.Balance
from d
inner join @t t
on(d.Id = t.Id
and d.MinSDate = t.SDate
);
输出:
Id | Balance
----+--------
ABC | 3
DEF | 7
GHI | 2
XYZ | 12
这应该是可能的窗口功能-所有你要做的是
- 按id分区
- 分配一个行号,然后
- 为每个id选择顶行
例如:
select id,
balance
from (
select id,
balance,
row_number() over( partition by id order by SDate ) as row_num
from table1
where SDate between '2016-01-01' and '2016-02-01'
) as a
where row_num = 1
注意:这种方法的优点是更灵活。假设您想要2条最早的记录,您可以更改为where row_num,您可以使用子查询
SELECT Id ,
( SELECT TOP 1
Balance
FROM [TableName] AS T1
WHERE T1.Id = [TableName].Id
ORDER BY SDate
) AS Balance
FROM [TableName]
GROUP BY Id;
您可以通过自连接来实现这一点,自连接可能不是最快或最优雅的解决方案:
CREATE TABLE #SOPostSample
(
SDate DATE ,
Id NVARCHAR(5) ,
Balance INT
);
INSERT INTO #SOPostSample
( SDate, Id, Balance )
VALUES ( '2016-01-01', 'ABC', 3 ),
( '2016-01-01', 'DEF', 7 ),
( '2016-01-01', 'GHI', 2 ),
( '2016-02-01', 'ABC', 6 ),
( '2016-02-01', 'DEF', 4 ),
( '2016-02-01', 'GHI', 8 ),
( '2016-02-01', 'XYZ', 12 );
SELECT t1.Id ,
MIN(t2.Balance) Balance
FROM #SOPostSample t1
INNER JOIN #SOPostSample t2 ON t1.Id = t2.Id
GROUP BY t1.Id ,
t2.SDate
HAVING t2.SDate = MIN(t1.SDate);
DROP TABLE #SOPostSample;
产生:
id Balance
============
ABC 3
DEF 7
GHI 2
XYZ 12
这适用于示例数据,但请使用更多数据进行测试,因为我刚刚快速编写了它。这应该可以工作,为安全起见刚刚插入的Top 1,如果SDate和Id在组合中是唯一的,则不需要
SELECT o.Id ,
( SELECT TOP 1
Balance
FROM tbl
WHERE Id = o.Id
AND SDate = MIN(o.SDate)
) Balance
FROM tbl o
GROUP BY Id
HAVING sDate BETWEEN '20160101' AND '20160201';
分析行数()
应该是最快的
select *
from (
select
t.*,
row_number() over (partition by Id order by SDate) rn
from your_table t
) t where rn = 1;
我假设Id+SDate是唯一的,否则您可能会有超过1个余额对不起,好的一点,让我快速更新我的问题您的select
语句中的Sub-select是一个巨大的性能杀手。您的select
语句中的Sub-select是一个巨大的性能杀手。
select *
from (
select
t.*,
row_number() over (partition by Id order by SDate) rn
from your_table t
) t where rn = 1;