考虑一个包含名称的数据库表,其中有三行:

Peter
Paul
Mary

有没有一种简单的方法可以把它变成彼得、保罗、玛丽的一串?


当前回答

这也很有用

create table #test (id int,name varchar(10))
--use separate inserts on older versions of SQL Server
insert into #test values (1,'Peter'), (1,'Paul'), (1,'Mary'), (2,'Alex'), (3,'Jack')

DECLARE @t VARCHAR(255)
SELECT @t = ISNULL(@t + ',' + name, name) FROM #test WHERE id = 1
select @t
drop table #test

回报

Peter,Paul,Mary

其他回答

使用“TABLE”类型非常容易。让我们假设您的表名为Students,并且它具有列名。

declare @rowsCount INT
declare @i INT = 1
declare @names varchar(max) = ''

DECLARE @MyTable TABLE
(
  Id int identity,
  Name varchar(500)
)
insert into @MyTable select name from Students
set @rowsCount = (select COUNT(Id) from @MyTable)

while @i < @rowsCount
begin
 set @names = @names + ', ' + (select name from @MyTable where Id = @i)
 set @i = @i + 1
end
select @names

此示例使用SQL Server 2008 R2进行了测试。

要避免空值,可以使用CONCAT()

DECLARE @names VARCHAR(500)
SELECT @names = CONCAT(@names, ' ', name) 
FROM Names
select @names

使用递归查询,您可以执行以下操作:

-- Create example table
CREATE TABLE tmptable (NAME VARCHAR(30)) ;

-- Insert example data
INSERT INTO tmptable VALUES('PETER');
INSERT INTO tmptable VALUES('PAUL');
INSERT INTO tmptable VALUES('MARY');

-- Recurse query
with tblwithrank as (
select * , row_number() over(order by name) rang , count(*) over() NbRow
from tmptable
),
tmpRecursive as (
select *, cast(name as varchar(2000)) as AllName from tblwithrank  where rang=1
union all
select f0.*,  cast(f0.name + ',' + f1.AllName as varchar(2000)) as AllName 
from tblwithrank f0 inner join tmpRecursive f1 on f0.rang=f1.rang +1 
)
select AllName from tmpRecursive
where rang=NbRow

我们可以使用RECUSRSIVITY、WITH CTE、union ALL,如下所示

declare @mytable as table(id int identity(1,1), str nvarchar(100))
insert into @mytable values('Peter'),('Paul'),('Mary')

declare @myresult as table(id int,str nvarchar(max),ind int, R# int)

;with cte as(select id,cast(str as nvarchar(100)) as str, cast(0 as int) ind from @mytable
union all
select t2.id,cast(t1.str+',' +t2.str as nvarchar(100)) ,t1.ind+1 from cte t1 inner join @mytable t2 on t2.id=t1.id+1)
insert into @myresult select *,row_number() over(order by ind) R# from cte

select top 1 str from @myresult order by R# desc

我在家里无法访问SQL Server,所以我猜测这里的语法,但大致上是这样的:

DECLARE @names VARCHAR(500)

SELECT @names = @names + ' ' + Name
FROM Names