SQL 列表串联
示例
部分归功于此SO答案。
列表串联通过将值组合成每个组的单个字符串来聚合列或表达式。可以指定用于分隔每个值的字符串（如果省略，则为空白或逗号），并且可以指定结果中值的顺序。尽管它不是SQL标准的一部分，但是每个主要的关系数据库供应商都以自己的方式支持它。
的MySQL
SELECT ColumnA
, GROUP_CONCAT(ColumnB ORDER BY ColumnB SEPARATOR ',') AS ColumnBs
FROM TableName
GROUP BY ColumnA
ORDER BY ColumnA;Oracle和DB2
SELECT ColumnA
, LISTAGG(ColumnB, ',') WITHIN GROUP (ORDER BY ColumnB) AS ColumnBs
FROM TableName
GROUP BY ColumnA
ORDER BY ColumnA;PostgreSQL的
SELECT ColumnA
, STRING_AGG(ColumnB, ',' ORDER BY ColumnB) AS ColumnBs
FROM TableName
GROUP BY ColumnA
ORDER BY ColumnA;SQL服务器
SQLServer2016及更早版本
（包括CTE以鼓励DRY原则）
WITH CTE_TableName AS (
SELECT ColumnA, ColumnB
FROM TableName)
SELECT t0.ColumnA
, STUFF((
SELECT ',' + t1.ColumnB
FROM CTE_TableName t1
WHERE t1.ColumnA = t0.ColumnA
ORDER BY t1.ColumnB
FOR XML PATH('')), 1, 1, '') AS ColumnBs
FROM CTE_TableName t0
GROUP BY t0.ColumnA
ORDER BY ColumnA;SQLServer2017和SQLAzure
SELECT ColumnA
, STRING_AGG(ColumnB, ',') WITHIN GROUP (ORDER BY ColumnB) AS ColumnBs
FROM TableName
GROUP BY ColumnA
ORDER BY ColumnA;SQLite的
无需订购：
SELECT ColumnA
, GROUP_CONCAT(ColumnB, ',') AS ColumnBs
FROM TableName
GROUP BY ColumnA
ORDER BY ColumnA;订购需要子查询或CTE：
WITH CTE_TableName AS (
SELECT ColumnA, ColumnB
FROM TableName
ORDER BY ColumnA, ColumnB)
SELECT ColumnA
, GROUP_CONCAT(ColumnB, ',') AS ColumnBs
FROM CTE_TableName
GROUP BY ColumnA
ORDER BY ColumnA;