SQL grouping results - sql

Question

I'm trying to get the last time a table was updated by the users:
Declare #Collect Table (Name Varchar(100),last_user_update datetime)
Insert into #Collect
EXEC sp_MSForEachTable 'SELECT ''?'' as TableName,
last_user_update
FROM sys.dm_db_index_usage_stats
WHERE database_id = DB_ID(''SP3D_DB_RESEARCH_MDB'') AND OBJECT_ID = OBJECT_ID(''?'')'
SELECT * FROM #Collect ORDER BY last_user_update DESC
The problem is that in the results, some tables are appearing 3 times (please see the image bellow)
Since it appears that all tables duplicated have the same last updated time. Is there any way to group the results by the table name?

Answer 1

If the values are indeed the same, you can just add DISTINCT to the query, and have it return unique results
SELECT DISTINCT ''?'' as TableName, last_user_update ...
If you want to group after the fact, and only the last update interests you, you can do
SELECT TableName, max(last_user_update) as last_update
FROM #Collect
GROUP BY TableName
ORDER BY 2 DESC

Answer 2

Tables can have multiple indexes. The dynamic management view sys.dm_db_index_usage_stats will have separate entries for each index.
If you want to see the index name for each one, try this:
SELECT
o.name as TableName,
i.name as IndexName,
istats.last_user_update
from sys.dm_db_index_usage_stats istats
inner join sys.objects o
on o.object_id = istats.object_id
inner join sys.indexes i
on i.index_id = istats.index_id
and i.object_id = istats.object_id
order by
o.name,
i.name
Or, if you don't care about that and just want the last update time, you can group by the table name:
SELECT
o.name as TableName,
max(istats.last_user_update)
from sys.dm_db_index_usage_stats istats
inner join sys.objects o
on o.object_id = istats.object_id
group by
o.name
You can do an insert directly into your table with this query:
declare #Collect table (Name varchar(100),last_user_update datetime)
insert into #Collect
select
o.name as TableName,
istats.last_user_update
from sys.dm_db_index_usage_stats istats
inner join sys.objects o
on o.object_id = istats.object_id
inner join sys.indexes i
on i.index_id = istats.index_id
and i.object_id = istats.object_id
where database_id = db_id('SP3D_DB_RESEARCH_MDB')
Also, I'm not sure what your goal is, but please understand that this view only has entries for indexes that have activity on them. If an index is unused, it is not in this view. The first access creates a row in the view. The real interesting stuff on this view is the seek and scan information.
See this note from MSDN:
When an index is used, a row is added to sys.dm_db_index_usage_stats
if a row does not already exist for the index. When the row is added,
its counters are initially set to zero.
If your goal is to enumerate all the indexes and then show the last update date for all of them, you'll need to join to sys.indexes and then left join to sys.dm_db_index_usage_stats.