使用2个表将多行汇总为单行

Question

Is there any way to change a SQL query that would normally return multiple rows with the same values into a single row as comma separated?

Table1
------
Col1
------
Sci-Fi
Action
Crime

Table2
------------
Col1 | Col2
------------
1    | Action
1    | Sci-Fi
2    | Crime
2    | Action
2    | Sci-Fi

And I need a query that results like this: (Table1 and Table2 combined)

----------------------------
Col1 |  Col2
----------------------------
1    | Action, Sci-Fi
2    | Crime, Action, Sci-Fi

Answer 1

SELECT MG.movie_id , STUFF(( SELECT ',' + G.genre_name FROM Movie_Genre AS G WHERE G.movie_id = MG.movie_id ORDER BY G.genre_name FOR XML PATH('') ), 1, 1, '') AS Genres FROM Movie_Genre AS MG GROUP BY MG.movie_id

感谢这个职位的疯狂真棒STUFF表达。

Answer 2

You can use STUFF function to combine multiple row as comma separated.

Sample SQl Fiddle

SELECT ID, col2 =
            stuff((
                   SELECT ','+ [col2] FROM t WHERE Id = t1.Id FOR XML PATH('')
                  ),1,1,'') 
FROM (SELECT DISTINCT ID FROM t ) t1

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