[dba-VB] Using the hash for real world problems

Answered on VB list.

On 19 Mar 2011 at 9:55, jwcolby wrote:

> I got into the hashing business in order to create a surrogate key of
> sorts, in fact a trio of them.
> 
> I have an address hash, a family hash and a person hash.  I compute
> these three hashes for every table of persons.  Now that I have these
> surrogate keys I have "identical" values in a single field where the
> input is identical in multiple fields.  Thus I do not have to do
> multi-field joins where I have a hash for all of those fields.
> 
> I am happy to hear that I am secure in my surrogate hash algorithm
> choice.
> 
> OK, so I have these hashes.  Every record has these three hashes.
> 
> Now some definitions:
> 
> HashAddr: A unique address is addr/zip5/zip4 different
> HashFamily: A unique family is LName/Addr/Zip5/Zip4 different
> HahsPerson: A unique person is FName/LName/Addr/Zip5/Zip4 different.
> 
> Using this information, I need to calculate the count of addresses
> with a single person, with two persons etc for as many combinations as
> I have.
> 
> Addresses	People
> 22,538,240	1
> 780,462,346	2
> 52,234		3 people
> etc
> etc till every quantity of people is found.
> 
> What is the simplest way to accomplish this with SQL.
> 
> 
> 
> 
> -- 
> John W. Colby
> www.ColbyConsulting.com
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