How can i get grouped data in Sub-Query

Question

I have Table with below data

Id      date
-----------------------------------
1       2014-06-11 08:35:00.000
2       2014-06-11 08:35:00.000
3       2014-06-11 08:50:00.000
4       2014-06-11 08:55:00.000
5       2014-06-11 08:55:00.000

I want to query and group the row by date and get below result

 date                            Ids
----------------------------------------
2014-06-11 08:35:00.000          1,2
2014-06-11 08:50:00.000          3
2014-06-11 08:55:00.000          4,5

for that I have wrote a query

SELECT dateadd(millisecond, - datepart(millisecond, EventDate) ,EventDate), COUNT(*),
STUFF((SELECT ',' + CAST(MetricEventId as varchar) FROM MetricEvents ME1  WHERE ME1.MetricEventId = ME.MetricEventId FOR XML PATH('')),1,1,'') FROM MetricEvents ME
GROUP BY dateadd(millisecond, - datepart(millisecond, EventDate) ,EventDate),EventUrl

but I am getting error message saying

Column 'MetricEvents.MetricEventId' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.

I know it wants me to group my query by MetricEvents.MetricEventId as well but that's not my requirement as I want to group them only by date, how can I get my grouped data in my sub query something like ME1.MetricEventId IN (GROUPED IDS) or is there any alternative

Answer 1

I guess this is what you are looking for:

SELECT t1.Date , (SELECT STUFF((SELECT ','+ cast(t2.id as nvarchar(5))
              FROM DemoTable t2 WHERE t2.Date = t1.Date
              FOR XML PATH('')), 1, 1, '')) as IDS
FROM DemoTable t1
GROUP By t1.Date

Depending on if you have milliseconds in your data, you can also subtract the milliseconds as in your own SQL query.

Fiddle Demo