MAX of two columns in one SQL

Posted on 2014-03-09
Medium Priority
Last Modified: 2014-03-09
I have the following Customer table:

Table structure
The desired output is:
CustomerId = 1
OrderDate = 02-FEB-2014
CustomerEmail = angel@yahoo.com

I need to get the latest order date and related email from this table.

I tried to do the following:
Select CustomerId, MAX(OrderDate) OVER (PARTITION BY CustomerID), MAX(CustomerEmail) OVER (PARTITION BY CustomerId)
FROM Customer table;

Open in new window

Though this sql is returning the MAX(orderDate) correctly, the MAX(CustomerEmail) returned is not the one associated to the Max(orderdate) but the one with highest alphabetical order (i.e, in this case Zy2013@yahoo.com).

How do I get both the MAX(OrderDate) and its associated CustomerEmail in the same query using MAX as well as OVER PARTITION by approach?

Question by:sath350163
  • 2
LVL 10

Expert Comment

ID: 39915785
Select CustomerId, MAX(OrderDate),CustomerEmail  OVER (PARTITION BY OrderDate), FROM Customer table;

Accepted Solution

Anoo S Pillai earned 1000 total points
ID: 39916033
If my understanding is correct, your logical requirement is to identify latest order by each customer and then get the related value.  So partition by should be based on CustomerID and OrderBy should be based on orderDate
ROW_number is the proper function for this requirement, something similar to the following would be useful.

select * 
   (  select * , 
       row_number () over ( partition by customerid order by orderdate desc )  as rownum 
       from customer
  ) DTab
where rownum = 1 

Open in new window

LVL 75

Expert Comment

by:Anthony Perkins
ID: 39916037
There are a couple of ways of doing that this is one:
SELECT  c.CustomerId, c.OrderDate, c.CustomerEmail
FROM    [Customer table] c
        INNER JOIN (SELECT  CustomerId,
                            MAX(OrderDate) LastOrderDate
                    FROM    [Customer table]
                    GROUP BY CustomerId
                   ) d ON c.CustomerId = d.CustomerId
                          AND c.OrderDate = d.LastOrderDate

Open in new window

LVL 75

Assisted Solution

by:Anthony Perkins
Anthony Perkins earned 1000 total points
ID: 39916049
Here is another approach using a CTE:
          AS (SELECT    CustomerId,
                        ROW_NUMBER() OVER (PARTITION BY CustomerId ORDER BY OrderDate DESC) Row
SELECT  CustomerId,
WHERE   Row = 1

Open in new window


Featured Post

The 14th Annual Expert Award Winners

The results are in! Meet the top members of our 2017 Expert Awards. Congratulations to all who qualified!

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

Join & Write a Comment

This article shows gives you an overview on SQL Server 2016 row level security. You will also get to know the usages of row-level-security and how it works
What if you have to shut down the entire Citrix infrastructure for hardware maintenance, software upgrades or "the unknown"? I developed this plan for "the unknown" and hope that it helps you as well. This article explains how to properly shut down …
Via a live example, show how to setup several different housekeeping processes for a SQL Server.
Viewers will learn how to use the UPDATE and DELETE statements to change or remove existing data from their tables. Make a table: Update a specific column given a specific row using the UPDATE statement: Remove a set of values using the DELETE s…

588 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question