列出連線

部分歸功於這個 SO 答案。

List Concatenation 通過將值組合為每個組的單個字串來聚合列或表示式。可以指定用於分隔每個值的字串（省略時為空白或逗號）以及結果中值的順序。雖然它不是 SQL 標準的一部分，但每個主要的關聯式資料庫供應商都以自己的方式支援它。

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

SELECT ColumnA
     , STRING_AGG(ColumnB, ',' ORDER BY ColumnB) AS ColumnBs
  FROM TableName
 GROUP BY ColumnA
 ORDER BY ColumnA;

SQL Server

SQL Server 2016 及更早版本

（包括 CTE 以鼓勵 DRY 原則 ）

  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;

SQL Server 2017 和 SQL Azure

SELECT ColumnA
     , STRING_AGG(ColumnB, ',') WITHIN GROUP (ORDER BY ColumnB) AS ColumnBs
  FROM TableName
 GROUP BY ColumnA
 ORDER BY ColumnA;

SQLite

沒有訂購：

SELECT ColumnA
     , GROUP_CONCAT(ColumnB, ',') AS ColumnBs
  FROM TableName
 GROUP BY ColumnA
 ORDER BY ColumnA;

訂購需要子查詢或 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;