在SQL Server中选择Group中的计数记录？

Question

我有一个wsm_Ref_Buildings表，其中包含buildingid，city列。我想看到所有州内的所有buildingid。例如：黑斯廷斯（city）有18个建筑物（count），我希望结果中包含所有18个buildingid。

查询

select count(BuildingId), city 
from wsm_Ref_Buildings 
group by City

Answer 1

试试这个

SELECT 
    City,
    BuildID,
    BuildCnt = COUNT(BuildingId) OVER(PARTITION BY City) from wsm_Ref_Buildings 

演示

DECLARE @T TABLE
(
    City VARCHAR(5),
    BuildID INT
)

INSERT INTO @T
VALUES('ABC',1),('ABC',2),('ABC',3),('XYZ',1),('XYZ',4),('HIJ',6)

SELECT
    City,
    BuildID,
    BuildCnt = COUNT(1) OVER(PARTITION BY City)
    FROM @T

输出

Answer 2

据我了解，您希望连接构建ID值并显示城市和建筑物数量， 请检查

select
    w.city,
    count(*) as cnt,
    stuff(
        (
            select ',' + convert(varchar(10),b.buildingid)
            from wsm_Ref_Buildings b
            where b.city = w.city
            FOR XML PATH('')
        ), 1, 1, ''
    ) as list
from wsm_Ref_Buildings w
group by w.city

对于SQL Server 2017之前的版本，这是string concatenation in SQL

如果您有SQL Server 2017，可以使用string_agg string aggregation function，如下所示

select
  city,
  count(*) as cnt,
  string_agg( convert(varchar(10), buildingid) , ',' ) within group (order by buildingid) as list
from wsm_Ref_Buildings
group by city

两个查询都将使用我的样本数据

创建以下输出

我希望它有所帮助

Answer 3

SELECT 
City,BuildID,
(select COUNT(WS.BuildingId) from  wsm_Ref_Buildings AS WS 
WHERE  WS1.City=WS.City) as  BuildCnt  
from wsm_Ref_Buildings AS WS1