SQLSERVER 中的 ListAGG

Question

我正在嘗試在 SQLServer 中聚合一個“字符串”字段。 我想在 Oracle 中找到相同的 function LISTAGG。

你知道如何做同樣的 function 或另一種方法嗎？

例如，

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

我希望這個查詢的結果是

1 | AB
2 | A

Answer 1

MySQL

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

甲骨文和 DB2

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

PostgreSQL

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

SQL 服務器

SQL Server ≥ 2017 & 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（包括 CTE 以鼓勵DRY 原則）

  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

排序需要 CTE 或子查詢

  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;

無需訂購

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

Answer 2

從SQL Server 2017開始，可以使用STRING_AGG函數，這大大簡化了邏輯：

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

請參閱帶有演示的 SQL Fiddle

在 SQL Server 中，您可以使用FOR XML PATH來獲取結果：

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;

請參閱帶有演示的 SQL Fiddle

Answer 3

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對於相反的情況很有用，並且在 SQL Server 2016 中可用

Answer 4

這可能對某人也有用..

即用於數據分析師和數據分析類型的目的..（即不分組）..

在 SQL*Server 2017 String_agg 函數存在之前..

（即只返回一行..）

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 

例如返回逗號分隔值 A,B