[AccessD] How would you cross index

roz.clarke at barclays.com roz.clarke at barclays.com
Mon Jun 7 09:29:39 CDT 2010


I don't have any better ideas than yours JC and maybe nobody does either
but I'm curious so I thought I'd give this a bit of a bump.

Roz 

-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of jwcolby
Sent: 04 June 2010 22:18
To: Access Developers discussion and problem solving; Sqlserver-Dba; VBA
Subject: [AccessD] How would you cross index

Imagine you had 10 tables of names / addresses.  Each table came from a
different source.  You could get more such tables at a moment's notice.
Each table has a different number of records, real life examples - 12
million, 23 million, 65 million, 75 million etc.

Each table has a autonumber PKID that (typically) starts at zero and
works up, incrementing by one.

Each table has three hash fields (SHA as it happens).
1) Addr / zip5 / zip4
2) LName / Addr / Zip5 / Zip4
3) FName / LName / Zip5 / Zip4

You wanted to cross index these tables.  In other words you wanted to
know how many exact matches you had (FName, LName, Addr, City, St, Zip5,
Zip4) between any given tables.

Further imagine that each table had additional DIFFERENT fields that
gave specific information about the names in that table.  One might be
"owns a dog / cat", another might be "has kids in age brackets..."

What method would you use to allow a cross index?

The only method that I am coming up with would be to have a name/Address
table with additional fields to store the PKID from each table.  Add
each unique name / address into the table one time. 
Use the name hash in inner joins to discover exact matches.  Update the
PKID fields in each column for the table(s) that the match(es) occur.
Add a new column every time you get a new table.

Your ideas?

--
John W. Colby
www.ColbyConsulting.com
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