SQLSERVER 中的 ListAGG

2021-12-01 00:00:00 sql aggregate sql-server

我正在尝试在 SQLServer 中聚合一个STRING"字段.我想在 Oracle 中找到与 LISTAGG 相同的函数.

I'm trying to aggregate a 'STRING' field in SQLServer. I would like to find the same function LISTAGG like in Oracle .

你知道如何做同样的功能或另一种方法吗?

Do you know how to do the same function or an another method?

例如

Field A | Field B
1       |  A
1       |  B
2       |  A

我希望这个查询的结果是

And I would like that the result of this query will be 

1 | AB
2 | A

推荐答案

从 SQL Server 2017 STRING_AGG 函数可用，大大简化了逻辑:

Starting in SQL Server 2017 the STRING_AGG function is available which simplifies the logic considerably:

select FieldA, string_agg(FieldB, '') as data
from yourtable
group by FieldA

参见SQL Fiddle with Demo

在 SQL Server 中，您可以使用 FOR XML PATH 来获取结果:

In SQL Server you can use FOR XML PATH to get the result:

select distinct t1.FieldA,
  STUFF((SELECT distinct '' + t2.FieldB
         from yourtable t2
         where t1.FieldA = t2.FieldA
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,0,'') data
from yourtable t1;

参见SQL Fiddle with Demo

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