Question

wasn’t sure whether to put this in Software or here, so I figured I’d start here I know this will be a straightforward answer from you SQL geniuses…

I have a table, it contains contacts that I import on a daily basis. I will have an ASP.NET front end for user interaction. From this table, my intention is to send them all mailers – but only one to each address. So my end result is a user enters a date (which corresponds to teh date imported) and they are given a resultant grid that has all the unique addresses associated to that date. I only want to send a mailer to that address once – many times my original imported list will contain multiple businesses at the same address.

Table: ContactTable
Fielsd:
ID, CompanyName, Address, City, State, Zip, Phone

I can use the SELECT DISTINCT clause, but I need all the data associated to it (company name, etc.)

I have over 262000 Records in this table.

If I select a sample date of 1/10/2011, I get 2401 records. SELECT DISTINCT Address from the same date gives me 2092 records. This is workable, I would send those 2092 people a mailer.

Secondly, I’d have to be able to historically check if a mailer was already sent to that address as well. I would not want to send another mailer to the same business tomorrow either.

What’s my best way?

Answer 1

I would select, then remove, the duplicates like this:

SELECT  a.ID, a.PurgedID, a.CAMPAIGNTYPE, a.COMPANY, a.DBANAME, a.COADDRESS, a.COCITY, a.COSTATE, a.COZIP, a.FIRSTNAME1, a.DIALERPHONENUM, a.Purged FROM PurgeReportDetail a
WHERE EXISTS (
    SELECT * FROM PurgeReportDetail b WHERE
    b.COADDRESS = a.COADDRESS
    AND b.COCITY = a.COCITY
    AND b.COSTATE = a.COSTATE
    AND b.COZIP = a.COZIP
    AND b.id <> a.id
    ) -- This clause will only include rows with duplicate columns noted
AND a.ID IN (
    SELECT TOP 1 c.ID from PurgeReportDetail c 
    WHERE c.COADDRESS = a.COADDRESS
    AND c.COCITY = a.COCITY
    AND c.COSTATE = a.COSTATE
    AND c.COZIP = a.COZIP
    ORDER BY c.ID -- If you want the *newest* entry to be saved, add "DESC" here
    ) -- This clause gets the top 1 ID value for each matching set

or something like this.
This will keep the first ID of the redundant address, just replace the SELECT with DELETE when ready.

EDIT: Of course this will only work on exact matches.

EDIT2: If you wanted to only check where you hadn’t sent mailers, you should join both to a table of sent mailers from a specified date range