Solved

SQL variable variables???

Posted on 2011-09-22
4
433 Views
Last Modified: 2012-06-27
DECLARE
@beginDate date = convert(varchar,DATEADD(MONTH,DATEDIFF(MONTH,0,getdate()),0),101),
@endDate Date = convert(varchar,DATEADD(MONTH,DATEDIFF(MONTH,-1,getdate()),-1),101);

with aggregate as

(select a, b, c
from Table
where processingDate between @beginDate and @endDate
union all
select a, b, c
from Table2
where processingDate between @beginDate and @endDate)

Select  sum(a), sum(b), sum(c)
from aggregate

What I would like to know is this.  How can I work with the variables properly so that I can do this as a monthly thing?  I want 6 months of data, meaning.... last months, then the month before that, then the month before that, etc.

What is the best way to approach this?  If I declare the variable as something fixed, it doesn't work.  I need to make the variable... variable... but how?
0
Comment
Question by:simplyfemales
  • 2
  • 2
4 Comments
 
LVL 59

Accepted Solution

by:
Kevin Cross earned 500 total points
ID: 36584433
Hi.

Is this is a rolling six months, i.e., when you run the report it should always give you the last full six months. For example running this today should give you August back to March. I would just get rid of the variables and put that into code; however, if you want the variables, note that you do not need to convert to US English format only to store as a Date which could care less about format. i.e., SQL does not store dates in a given format. That is strictly a display issue.

So these are the values you need:
DECLARE @beginDate AS DATE = DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE())-6, 0),
@endDate AS DATE = DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE()), 0);

You would then use then in your query as:
WHERE processingDate >= @beginDate AND  processingDate < @endDate

The @endDate is the first day of the current month at midnight, so the < is intentional. This helps with data that has timestamps as it will include all timestamps from the previous day up to but not including midnight. I guess if this is a date column, the between is fine, just make it:
WHERE processingDate BETWEEN @beginDate AND DATEADD(DAY, -1, @endDate)

Then I would GROUP BY DATEDIFF(MONTH, 0, processingDate), so that you get your sums for each of the six months in one report that you can convert back to a DATE for display (i.e., first day of each month). Another option is to show as month's ago, by doing your DATEDIFF(MONTH, processingDate, GETDATE()). Then you can consistently report on 1, 2, 3, 4, 5, or 6 months ago without worrying about actual date name.

Hope that helps!
0
 

Author Comment

by:simplyfemales
ID: 36584504
so I need to include ProcessingDate as a part of the select statements correct?  
0
 
LVL 59

Expert Comment

by:Kevin Cross
ID: 36584622
Correct, except you want to use one of the variations I showed using DATEDIFF() or else you will get sums by day instead of by month.
0
 

Author Closing Comment

by:simplyfemales
ID: 36588375
This is excellent.  Exactly what I need.  It reminded me of how basic the queries need to be sometimes.... just go back to what you know rather than trying to overthink it.
0

Featured Post

Free Tool: Subnet Calculator

The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

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

Long way back, we had to take help from third party tools in order to encrypt and decrypt data.  Gradually Microsoft understood the need for this feature and started to implement it by building functionality into SQL Server. Finally, with SQL 2008, …
In this article I will describe the Copy Database Wizard method as one possible migration process and I will add the extra tasks needed for an upgrade when and where is applied so it will cover all.
Microsoft Active Directory, the widely used IT infrastructure, is known for its high risk of credential theft. The best way to test your Active Directory’s vulnerabilities to pass-the-ticket, pass-the-hash, privilege escalation, and malware attacks …
The Email Laundry PDF encryption service allows companies to send confidential encrypted  emails to anybody. The PDF document can also contain attachments that are embedded in the encrypted PDF. The password is randomly generated by The Email Laundr…

861 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