sql 行合并

CREATE TABLE tent (
    [item] [int] NOT NULL,
    [aa] [int] NOT NULL,
    [bb] [varchar](50) NOT NULL
) ON [PRIMARY]

insert into tent(item,aa,bb) values(1,22,'good')
insert into tent(item,aa,bb) values(1,23,'very')
insert into tent(item,aa,bb) values(1,20,'very')
insert into tent(item,aa,bb) values(2,50,'ok')
insert into tent(item,aa,bb) values(3,15,'hello')

SELECT item,SUM(aa) as sum_aa,
STUFF((SELECT ''+bb FROM tent WHERE item=a.item FOR XML PATH('')),1,0,'') as bb
FROM tent a
GROUP BY item