在单个查询中收集有关表的多个统计信息

Question

假设我在MSSQL表中有这些数据

type      status       
a         open
b         open
a         closed
a         closed
a         closed
b         open
c         closed

我可以运行此查询来获取这样的表 select type,count(*) from table where status = 'open'

a     1
b     2

然后我可以再做一次查询 select type,count(*) from table where status = 'closed'

a          2
c          1

如何编写一个向我显示此类表格的查询

type        open         closed
a            1             2
b            2             0
c            0             1

Answer 1

这将产生您想要的结果

select type,
    SUM(case when status = 'open' then 1 else 0 end) as [Open],
    SUM(case when status = 'closed' then 1 else 0 end) as [Closed]
from table
group by type

Answer 2

您可以使用PIVOT，查看BOL或搜索任何SQL网站以获取一些使用示例。

Answer 3

在SQL 2005中创建了表，并使用pivot命令确认了以下工作：

select * 
from (select type, status from table) test 
pivot ( count(status) for status in ([Open], [Closed] )) pivottable