Want to win a PS4? Go Premium and enter to win our High-Tech Treats giveaway. Enter to Win

x
Solved

# MAX of two columns in one SQL

Posted on 2014-03-09
Medium Priority
350 Views
Hello,
I have the following Customer table:

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;
``````

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?

Thanks!
0
Question by:sath350163
[X]
###### Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

• Help others & share knowledge
• Earn cash & points
• Learn & ask questions
• 2

LVL 10

Expert Comment

ID: 39915785
Select CustomerId, MAX(OrderDate),CustomerEmail  OVER (PARTITION BY OrderDate), FROM Customer table;
0

LVL 7

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 *
from
(  select * ,
row_number () over ( partition by customerid order by orderdate desc )  as rownum
from customer
) DTab
where rownum = 1
``````
0

LVL 75

Expert Comment

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
``````
0

LVL 75

Assisted Solution

Anthony Perkins earned 1000 total points
ID: 39916049
Here is another approach using a CTE:
``````;WITH    CTE
AS (SELECT    CustomerId,
OrderDate,
CustomerEmail,
ROW_NUMBER() OVER (PARTITION BY CustomerId ORDER BY OrderDate DESC) Row
)
SELECT  CustomerId,
OrderDate,
CustomerEmail
FROM    CTE
WHERE   Row = 1
``````
0

## Featured Post

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

An alternative to the "For XML" way of pivoting and concatenating result sets into strings, and an easy introduction to "common table expressions" (CTEs). Being someone who is always looking for alternatives to "work your data", I came across this …
One of the most important things in an application is the query performance. This article intends to give you good tips to improve the performance of your queries.
Via a live example, show how to set up a backup for SQL Server using a Maintenance Plan and how to schedule the job into SQL Server Agent.
Viewers will learn how to use the SELECT statement in SQL and will be exposed to the many uses the SELECT statement has.
###### Suggested Courses
Course of the Month9 days, 14 hours left to enroll

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

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