SQL how to select latest dates from all entries

This SQL Table:
CREATE TABLE [dbo].[replication2](
      [id] [smallint] IDENTITY(1,1) NOT NULL,
      [VMName] [varchar](50) NULL,
      [PrimaryHost] [varchar](50) NULL,
      [ReplicaHost] [varchar](50) NULL,
      [LastReplicaDate] [varchar](50) NULL,
      [LastReplicaDateTime] [datetime2](7) NULL,

This table contains thousands of rows, each row representing a single instance of VM replication such as:

id      VMName      PrimaryHost      ReplicaHost      LastReplicaDate                  LastReplicaDateTime
1608      vm1      hostA            hostB            6/13/2015 8:44:37 am      2015-06-13 08:44:37.0000000

I would like to select all [VMName, PrimaryHost, ReplicaHost] such that for each unique [VMName, PrimaryHost, ReplicaHost] I only get the latest row, based on LastReplicaDateTime.

I've tried different group-by having methods but can't come up with anything that works.

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Jim HornMicrosoft SQL Server Data DudeCommented:
Give this a whirl..
SELECT VMName, PrimaryHost, ReplicaHost, Max(LastReplicaDateTime) as max_time
FROM replication2
GROUP BY VMName, PrimaryHost, ReplicaHost
ORDER BY VMName, PrimaryHost, ReplicaHost

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Check out my article called SQL Server GROUP BY Solutions for an image and code-heavy tutorial on GROUP BY and HAVING.

If the above doesn't meet your requirements, then you'll have to spell out in greater detail what are are asking.  Preferably with before-and-after data mockups.

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PortletPaulEE Topic AdvisorCommented:
I recommend using ROW_NUMBER() when you want the whole row associated with a "latest" (or "earliest")  date

While grouping will efficiently determine the latest date, it is less efficient when it comes to getting the whole row associated with that date. Whereas when using ROW_NUMBER() this isn't a problem and is efficient.

      VMName, PrimaryHost, ReplicaHost, LastReplicaDateTime
            ROW_NUMBER() OVER (PARTITION BY VMName, PrimaryHost, ReplicaHost
                               ORDER BY LastReplicaDateTime DESC) AS rn
          , VMName
          , PrimaryHost
          , ReplicaHost
          , LastReplicaDateTime
      FROM replication2
      ) R
WHERE rn = 1

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HuaMin ChenProblem resolverCommented:
group by Name, PrimaryHost, ReplicaHost,max(lastreplicadate),max(lastreplicadatetime)

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awking00Information Technology SpecialistCommented:
I agree with the row_number() method since it will also allow you to get the id and LastReplicaDate (i.e. the entire row) without having to include them in a group by clause.
Vitor MontalvãoMSSQL Senior EngineerCommented:
gateguard, do you still need help with this question?
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