[mysql] 之於MSSQL XML PATH

在MSSQL中，要合併多筆資料到同一個欄位

可以用 XML PATH來實現

SELECT T1.id, T1.type
          ,(SELECT [DESC] + ''
          FROM   @TABLE AS T2
          WHERE  T2.id = T1.id  FOR XML PATH('')) AS [DESC]
FROM @TABLE AS T1
GROUP BY id, type

而在MYSQL中，可以用GROUP_CONCAT來實現

SELECT date_format(T.T1,'%Y%m') AS d
              ,GROUP_CONCAT(T.ID) AS id
FROM @TABLE AS T
GROUP BY date_format(T.T1,'%Y%m')