What is recursion?

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What is recursion?

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Alan Burstein SSC Guru Points: 61136 More actions · Answer 1

Based on this thread it sounds as if you are dealing with a recursive CTE and I think you've received pretty good input.

With respect to SQL Server the only benefit I've seen to understanding recursion is that you can troubleshoot someone else's poorly performing code. If you ever get into functional programming (the article Sean posted makes mention of this) understanding recursion is important because functional programming languages are optimized for recursion.

Outside of that I think it's a cool mathematical concept.

"I cant stress enough the importance of switching from a sequential files mindset to set-based thinking. After you make the switch, you can spend your time tuning and optimizing your queries instead of maintaining lengthy, poor-performing code."

-- Itzik Ben-Gan 2001

MMartin1 One Orange Chip Points: 27655 More actions · Answer 2

I did a quick search and looked through a few links on recursion. Here is one that I think explains the basics fairly well from a elementary standpoint.

http://www.cplusplus.com/articles/D2N36Up4/

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Eirikur Eiriksson SSC Guru Points: 182631 More actions · Answer 3

As I see it Recursion in T-SQL is like paying taxes, something we would all like to avoid but some(read most)times that's not possible.

😎

Chris Wooding SSCarpal Tunnel Points: 4427 More actions · Answer 4

To answer the original question; this

http://qa.sqlservercentral.com/Forums/Topic1752249-1292-1.aspx

is recursion.

MMartin1 One Orange Chip Points: 27655 More actions · Answer 5

Chris Wooding (1/21/2016)
To answer the original question; this
http://qa.sqlservercentral.com/Forums/Topic1752249-1292-1.aspx
is recursion.

I would also call that an infinite loop. A Recursive function should have a cut off point. 😛

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Luis Cazares SSC Guru Points: 183686 More actions · Answer 6

MMartin1 (1/21/2016)
Chris Wooding (1/21/2016)
To answer the original question; this
http://qa.sqlservercentral.com/Forums/Topic1752249-1292-1.aspx
is recursion.
I would also call that an infinite loop. A Recursive function should have a cut off point. 😛

There is one, when you get tired of being redirected to the same place over and over.

Luis C.
General Disclaimer:
Are you seriously taking the advice and code from someone from the internet without testing it? Do you at least understand it? Or can it easily kill your server?

How to post data/code on a forum to get the best help: Option 1 / Option 2

j-1064772 SSCertifiable Points: 5316 More actions · Answer 7

The key question of recursion is in which cases is it the best approach ?

I remember the infamous factorial example - convenient to use to explain recursion in this very simple case. But often no warning given that this is the most inefficient way of calculating factorials. In fact, given the overhead involved, it is downright stupid to use recursion for factorials.

So when is the overhead warranted ?