ListAGG in SQLSERVER
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
See SQL Fiddle with Demo
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;
See SQL Fiddle with Demo
MySQL
SELECT FieldA
, GROUP_CONCAT(FieldB ORDER BY FieldB SEPARATOR ',') AS FieldBs
FROM TableName
GROUP BY FieldA
ORDER BY FieldA;
Oracle & 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 Server
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 (CTE included to encourage the DRY principle)
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
Ordering requires a CTE or subquery
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;
Without ordering
SELECT FieldA
, GROUP_CONCAT(FieldB, ',') AS FieldBs
FROM TableName
GROUP BY FieldA
ORDER BY FieldA;
In SQL Server 2017 STRING_AGG is added:
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
Also, STRING_SPLIT is usefull for the opposite case and available in SQL Server 2016