SQL Server：如何为group by语句

Question

我想为group by语句中的聚合列的不同事件生成逗号分隔的字符串。所以我有：

Select Column1, ???statement involving Column2??? from MyTable
group by Column1

我无法弄清问问题之间的内容。

Answer 1

假设您有以下表格：

use TSQL2012

    if object_id('testStackOverflow') is not null drop table testStackOverflow
    create table testStackOverflow(
    column1 varchar(100) not null,
    column2 varchar(100) not null,
    constraint PK2 primary key(column1,column2)

    )

    insert into testStackOverflow(column1,column2)
    values 
    ('value1','t1'),
    ('value1','t2'),
    ('value1','t3'),
    ('value2','t5'),
    ('value2','t6'),
    ('value2','t7')

您可以使用以下查询：

   Select column1, 
    substring(
        (
            Select ','+sto2.column2  AS [text()]
            From testStackOverflow as sto2
            Where sto2.column1 = sto1.column1
            ORDER BY sto2.column1
            For XML PATH ('')
        ), 2, 1000) as column2concat
From testStackOverflow as sto1
group by column1

结果将是：

我使用Ritesh的回答作为参考：  https://code.google.com/p/gdata-issues/issues/detail?id=4294