一列をすべてCSVにする方法。
┌──────────────────────────────────────┐
│WITH [表] (                                                                 │
│         [列]                                                               │
│     ) AS (                                                                 │
│         SELECT [列]                                                        │
│             FROM (                                                         │
│                 VALUES ('A'),('B'),('C')                                   │
│             ) AS [表]([列])                                                │
│     )                                                                      │
│SELECT REPLACE((SELECT [表].[列] AS [data()]                                │
│                    FROM [表]                                               │
│                    FOR XML PATH ('')       ), ' ', ',') AS [列たち];       │
└──────────────────────────────────────┘