[AccessD] Slow day - normalization discusion

Surely the degree of repetition depends on the homogeneity of the data - are
the phone numbers likely to all be from the same area? Or are the entries in
the database geographically widespread? 

If the numbers in the database are not clustered in the areas, having the
same prefix codes, it won't make sense to pull the prefixes out. I don't know
the exact mechanics of why, but I wouldn't separate data into another table
unless the new table was going to contain significantly fewer rows than the
original. You also have to account for how much this will speed up searches
etc. versus the burden of performing the join slowing updates etc.

-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of John Bartow
Sent: 18 June 2008 16:35
To: 'Access Developers discussion and problem solving'
Subject: [AccessD] Slow day - normalization discusion

I recently had pull data from a contact mgt. app's database where the
normalization brought up a question in my mind. The phone information was
normalized as:

tblPhone:
fldPhoneID (PK)
fldPhoneTypeID (FK)
fldAreaCodeID (FK)
fldPhoneNumber
fldPhoneExtension

tblPhoneType:
fldPhoneTypeID (PK)
fldPhoneType

tblAreaCode:
fldAreaCodeID (PK)
fldAreaCode

To be consistent with this level of normalization wouldn't it make sense to
have the first three numbers separated from the back 4 numbers? The first
three would be very repetitious also. So the table would appear as:

tblPhone:
fldPhoneID (PK)
fldPhoneTypeID (FK)
fldAreaCodeID (FK)
fldPhoneNumberPrefixID  (FK)
fldPhoneNumber
fldPhoneExtension

tblPhoneType:
fldPhoneTypeID (PK)
fldPhoneType

tblAreaCode:
fldAreaCodeID (PK)
fldAreaCode

tblPhonePrefix:
fldPhoneNumberPrefixID  (PK)
fldPhoneNumberPrefix


--
AccessD mailing list
AccessD at databaseadvisors.com
http://databaseadvisors.com/mailman/listinfo/accessd
Website: http://www.databaseadvisors.com

This e-mail and any attachments are confidential and intended solely for the addressee and may also be privileged or exempt from disclosure under applicable law. If you are not the addressee, or have received this e-mail in error, please notify the sender immediately, delete it from your system and do not copy, disclose or otherwise act upon any part of this e-mail or its attachments.

Internet communications are not guaranteed to be secure or virus-free.
The Barclays Group does not accept responsibility for any loss arising from unauthorised access to, or interference with, any Internet communications by any third party, or from the transmission of any viruses. Replies to this e-mail may be monitored by the Barclays Group for operational or business reasons.

Any opinion or other information in this e-mail or its attachments that does not relate to the business of the Barclays Group is personal to the sender and is not given or endorsed by the Barclays Group.

Barclays Bank PLC.Registered in England and Wales (registered no. 1026167).
Registered Office: 1 Churchill Place, London, E14 5HP, United Kingdom.

Barclays Bank PLC is authorised and regulated by the Financial Services Authority.