T-SQL: Rookie Question on Best Approach for Selecting

Posted on 2011-09-20
Last Modified: 2012-05-12
I'm looking for the best approach on identifying, then deleting, some customer data.  

There's tables for basic customer info, telephone/email info, and marketing info.  Some customers have email info, some don't.  The problem I'm trying to deal with is identifying those customers who don't an email address, yet have asked us to email them marketing info.  

My select statement is:
SELECT entity.entity_id,  phone.phone_no, phone.phone_type, attr_ent.attr_val
FROM   (entity entity INNER JOIN attr_ent attr_ent ON (entity.entity_id=attr_ent.entity_id) AND (entity.co_cd=attr_ent.co_cd))
LEFT OUTER JOIN phone phone ON entity.phone_id=phone.phone_id
WHERE  attr_ent.attr_val LIKE 'e-%'

It gets me data like:
00001003        NULL                           NULL      E-Newsletter        
00001003        NULL                           NULL      E-Training Updates  
00001035        952-123-4567      Direct      E-Newsletter        
00001035      Email      E-Newsletter        
00001035        952-123-4567      Direct      E-Training Updates  
00001035      Email      E-Training Updates  
00001240        507-321-9876      Fax      E-Newsletter        
00001240        507-321-9876      Fax      E-Training Updates  

Customer numbers 00001003 and 00001240 should have their requesst for marketing info deleted, as there's no where to send it.  However, customer 00001035, has an email address and should get the marketing info.

I'm getting stuck doing the deletes on customers like 00001035 because I can't figure out how to identify them as valid requests.
Question by:anordquist
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LVL 18

Expert Comment

ID: 36568584
could you do something like

DELETE entity WHERE entity.entity_id IN(
SELECT entity.entity_id
FROM   (entity entity INNER JOIN attr_ent attr_ent ON (entity.entity_id=attr_ent.entity_id) AND (entity.co_cd=attr_ent.co_cd))
LEFT OUTER JOIN phone phone ON entity.phone_id=phone.phone_id
WHERE  attr_ent.attr_val LIKE 'e-%'  AND phone.phone_no IS NULL AND phone.phone_type IS NULL)


Author Comment

ID: 36570057
The marketing info is in the attribute table.  There's one row per customer per marketing info type.  I  can delete the row safely if the phone.phone_type is NULL, but what happens when the check comes up with a phone.phone_type equal to "Phone" rather than to "E-Mail".  The attribute table row gets deleted, even if there might be a later record in the phone table for that customer that has the email info.

These aren't the exact names for the columns
               customer table

Author Comment

ID: 36570098
The prior comment got away from me.....

Customer table

Phone table      (used for phone, fax, website, email, etc.)

Attribute-customer table

Attribute table

So, if a customer doesn't have an email address, yet has requested marketing info, I want to delete the corresponding row in the attribute-customer table.  I need to be able to check all of the rows in the phone table for the customer before I can determine if a deletion is warranted.
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LVL 21

Expert Comment

by:Alpesh Patel
ID: 36573150
Use Merge statement of SQL Server 2008 R2.

Merge Souce

When Match
When not MAtche

Author Comment

ID: 36573700
I'm running SQL Server 2005.

Accepted Solution

anordquist earned 0 total points
ID: 36905683
Delete question, no solutions are forthcoming.

Author Closing Comment

ID: 36935287
Delete the question, no answers for SQL Server 2005.

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