Question

我有一个表，包含两列：

Column1  Column2
a        g
b        null
a        e
null     g
d        null
...      ...

对于每个Column1，我想得到一个以分号分隔的Column2值列表，所以这是我的代码：

select
    coalesce(t1.Column1, 'Empty') as col1,
    (
        select
            t2.Column2 + '; '
        from
            table as t2
        where
            t2.Column1 = t1.Column1
        for xml path(N'')
    ) as col2list
from
    table as t1

当然，当t1.Column1为null时，内部查询不会返回任何内容，因为null不等于null。但是，当Column1为null时，我需要获取Column2的这些值，并将其显示在＆＃39; Empty＆＃39;字。知道如何做到这一点吗？

提前致谢。

Answer 1

试

select
    coalesce(t1.Column1, 'Empty') as col1,
    (
        select
            isnull(t2.Column2,'') + '; '
        from
            table as t2
        where
            isnull(t2.Column1,'') = isnull(t1.Column1,'')
        for xml path(N'')
    ) as col2list
from
    table as t1

Answer 2

在where子句中添加另一个条件：

select
    coalesce(t1.Column1, 'Empty') as col1,
    (
        select
            t2.Column2 + '; '
        from
            table as t2
        where
            t2.Column1 = t1.Column1
        or 
            (t2.Column1 is null and t1.Column1 is null)
        for xml path(N'')
    ) as col2list
from
    table as t1

Answer 3

Try this 首先设置空值，以便您可以配对它们。

如何在t-sql

3 个答案: