SQLSERVER中的ListAGG

我正在尝试在SQLServer中聚合“ STRING”字段。我想找到与Oracle中相同的函数LISTAGG。

您知道如何执行相同的功能或其他方法吗？

例如，

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

我希望这个查询的结果是

1 | AB
2 | A

从SQL Server 2017开始，该STRING_AGG功能可用，从而大大简化了逻辑：

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

参见带有演示的SQL Fiddle

在SQL Server中，您可以FOR XML PATH用来获取结果：

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;

参见带有演示的SQL Fiddle

的MySQL

SELECT FieldA
     , GROUP_CONCAT(FieldB ORDER BY FieldB SEPARATOR ',') AS FieldBs
  FROM TableName
 GROUP BY FieldA
 ORDER BY FieldA;

Oracle和DB2

SELECT FieldA
     , LISTAGG(FieldB, ',') WITHIN GROUP (ORDER BY FieldB) AS FieldBs
  FROM TableName
 GROUP BY FieldA
 ORDER BY FieldA;

PostgreSQL的

SELECT FieldA
     , STRING_AGG(FieldB, ',' ORDER BY FieldB) AS FieldBs
  FROM TableName
 GROUP BY FieldA
 ORDER BY FieldA;

SQL服务器

SQL Server≥2017和Azure SQL

SELECT FieldA
     , STRING_AGG(FieldB, ',') WITHIN GROUP (ORDER BY FieldB) AS FieldBs
  FROM TableName
 GROUP BY FieldA
 ORDER BY FieldA;

SQL Server≤2016（包含CTE以鼓励DRY原则）

  WITH CTE_TableName AS (
       SELECT FieldA, FieldB
         FROM TableName)
SELECT t0.FieldA
     , STUFF((
       SELECT ',' + t1.FieldB
         FROM CTE_TableName t1
        WHERE t1.FieldA = t0.FieldA
        ORDER BY t1.FieldB
          FOR XML PATH('')), 1, LEN(','), '') AS FieldBs
  FROM CTE_TableName t0
 GROUP BY t0.FieldA
 ORDER BY FieldA;

SQLite的

订购需要CTE或子查询

  WITH CTE_TableName AS (
       SELECT FieldA, FieldB
         FROM TableName
        ORDER BY FieldA, FieldB)
SELECT FieldA
     , GROUP_CONCAT(FieldB, ',') AS FieldBs
  FROM CTE_TableName
 GROUP BY FieldA
 ORDER BY FieldA;

无需订购

SELECT FieldA
     , GROUP_CONCAT(FieldB, ',') AS FieldBs
  FROM TableName
 GROUP BY FieldA
 ORDER BY FieldA;

在SQL Server 2017中添加了STRING_AGG：

SELECT t.name,STRING_AGG (c.name, ',') AS csv
FROM sys.tables t
JOIN sys.columns c on t.object_id = c.object_id
GROUP BY t.name
ORDER BY 1

此外，STRING_SPLIT对于相反的情况也很有用，并且在SQL Server 2016中可用

这也可能对某人有用。

即用于数据分析人员和数据分析的目的类型..（即未分组）。

SQL * Server 2017之前的String_agg函数存在..

（即仅返回一行..）

select distinct
SUBSTRING (
stuff(( select distinct ',' + [FieldB] from tablename order by 1 FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)') 
,1,0,'' ) 
,2,9999)
from 
    tablename 

例如，返回逗号分隔的值A，B