sql获取group数量
现有表如下：
id money user_id project_id
11000.00 1 1
21000.00 1 1
3500.00 1 1
我现在要根据project_id来分组 ，并获得分组的组数的数量。
我现在的slq是：select count(*) from invest_log vl where vl.project_id = 1 group by user_id
得到的结果是3 ，不是我想要的结果 。 正确应该为1
sql该如何改？
[解决办法]
select count(*)
from (select distinct user_id,project_id from invest_log) as vl
where vl.project_id = 1 group by user_id
[解决办法]
----------------------------
-- Author :DBA_Huangzj(發糞塗牆)
-- Date :2013-09-20 09:43:07
-- Version:
-- Microsoft SQL Server 2014 (CTP1) - 11.0.9120.5 (X64)
--Jun 10 2013 20:09:10
--Copyright (c) Microsoft Corporation
--Enterprise Evaluation Edition (64-bit) on Windows NT 6.2 <X64> (Build 9200: ) (Hypervisor)
--
----------------------------
--> 测试数据：[huang]
if object_id('[huang]') is not null drop table [huang]
go
create table [huang]([d] int,[money] numeric(6,2),[user_id] int,[project_id] int)
insert [huang]
select 1,1000.00,1,1 union all
select 2,1000.00,1,1 union all
select 3,500.00,1,1
--------------开始查询--------------------------
select COUNT(DISTINCT(project_id))
from [huang]
----------------结果----------------------------
/*
-----------
1
*/
select * from(
select row_number()over(partition by project_id order by project_id)num,* from invest_log)a
where num=1
select count(user_id) as group_num from
(select user_id from invest_log vl where vl.project_id = 1 group by user_id) t
