Sql query for specific data

I have an Archive Table. The columns are PK, Users and Logdatetime. When Users log in the system i am writing to archive table the user and datetime. A user can login more than one in one day.

The data in Logd开发者_JAVA百科atetime is like '2010-03-16 00:00:00.000'

I need to query all users FIRST Login time in one day and get the user with the datetime like: user1 '2010-03-16 03:21:00.000' user2 '2010-03-16 04:11:00.000'

It does not matter the users order. I tried too many way but couldnt find a way. The only solution i found is the query for all users one by one. But it will take time. Any idea how to do this with a one query or more efficent way?

PS: I am using MS SQL Server 2005

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Do you mean that you want the users very first login or the just first of a specific day?

This example query might lead you in the right direction;

SELECT [User], MIN(LogDateTime) AS FirstLogin FROM [Archive Table] GROUP BY [User]