将空值和空值分组为sql中的值

Question

我有一个查询，它提供了应用于数据库中的事物的不同类别的细分：

select categories, count(*) from products 
group by categories

数据如下：

NULL                56
                    42
FooCategory         12
BlahCategory        2

我想将NULL和<blank>分组

NoCategory          98
FooCategory         12
BlahCategory        2

Answer 1

尝试

select ISNULL(categories,'') as Categories, count(*) from products 
group by ISNULL(categories,'')

UPDATE

请参阅此处了解所需参数

ISNULL（check_expression，replacement_value）

Answer 2

尝试

select categories, 
case when categories is null or categories = ' ' 
then 'noCategory' else categories end as grouped,
count(*) 
from products 
group by grouped