SQL Clone
SQLServerCentral is supported by Redgate
 
Log in  ::  Register  ::  Not logged in
 
 
 


Coin combinations


Coin combinations

Author
Message
dwain.c
dwain.c
SSCertifiable
SSCertifiable (7.6K reputation)SSCertifiable (7.6K reputation)SSCertifiable (7.6K reputation)SSCertifiable (7.6K reputation)SSCertifiable (7.6K reputation)SSCertifiable (7.6K reputation)SSCertifiable (7.6K reputation)SSCertifiable (7.6K reputation)

Group: General Forum Members
Points: 7571 Visits: 6431
L' Eomot Inversé (11/23/2013)


The idea of building tuples and then using a splitter to pull them apart looks promising. I am going to have a look and see if I gets me where I want to be, ie in a position to do early pruning for the case where all the joins are necessary because none of the conditions for alternative algorithms are satisfied without losing the ability to cope with a fairly unlimited variable number of denominations. I think I will have to either invent some rules such as no two denominations may be coprime and no denomination can be more than 500 times the smallest denomination, or have a much smaller limits on number of coins, though.


Tom - Your analysis was spot on. I couldn't make it work using the approach I tried.

Looks to me like you've already done a pretty dynamite job with your cascading CTEs. Didn't look in detail at what MM posted above, but yours smokes anything I was able to come up with.

Nice one!


My mantra: No loops! No CURSORs! No RBAR! Hoo-uh!

My thought question: Have you ever been told that your query runs too fast?

My advice:
INDEXing a poor-performing query is like putting sugar on cat food. Yeah, it probably tastes better but are you sure you want to eat it?
The path of least resistance can be a slippery slope. Take care that fixing your fixes of fixes doesn't snowball and end up costing you more than fixing the root cause would have in the first place.


Need to UNPIVOT? Why not CROSS APPLY VALUES instead?
Since random numbers are too important to be left to chance, let's generate some!
Learn to understand recursive CTEs by example.
Splitting strings based on patterns can be fast!
My temporal SQL musings: Calendar Tables, an Easter SQL, Time Slots and Self-maintaining, Contiguous Effective Dates in Temporal Tables
Go


Permissions

You can't post new topics.
You can't post topic replies.
You can't post new polls.
You can't post replies to polls.
You can't edit your own topics.
You can't delete your own topics.
You can't edit other topics.
You can't delete other topics.
You can't edit your own posts.
You can't edit other posts.
You can't delete your own posts.
You can't delete other posts.
You can't post events.
You can't edit your own events.
You can't edit other events.
You can't delete your own events.
You can't delete other events.
You can't send private messages.
You can't send emails.
You can read topics.
You can't vote in polls.
You can't upload attachments.
You can download attachments.
You can't post HTML code.
You can't edit HTML code.
You can't post IFCode.
You can't post JavaScript.
You can post emoticons.
You can't post or upload images.

Select a forum

































































































































































SQLServerCentral


Search