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From:David Kramer Date:July 30 2002 7:57pm
Subject:RE: removing duplicate records
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You could always use an insert statement into a second table, when
performing the insert use a GROUP BY clause to consalidate your records

something along these lines but this isnt 100% accurate, I would need the
table DDL and business rules behind the DEDUP

Insert into tableB
	column names, ...

	column a,
	column b,
	max(column c), --or you could use MIN
	table A

group by 
	column a,
	column b);

**JUST make sure your Identifing column, i.e. the column you use to tell
which is a duplicate record or not is included in the group by.  Also what
are the business rules behind the DEDUP(Deduplication)? Are the other values
contained in the other columns necessary?  If you tell me more about what
your trying to do and provide some Table DDL I can help you write this
query.  Just let me know!



  group by statement 

-----Original Message-----
From: walt [mailto:walt@stripped]
Sent: Tuesday, July 30, 2002 12:43 PM
To: mysql@stripped
Subject: removing duplicate records

Does anyone know a good way find and remove duplicate records from a table?
I can create an identical table structure and use a script to pull records 
from the existing table and insert them into the new table if they are not 
duplicates, but I'd rather not do it that way. Here is an example of an sql 
script  I use for Oracle databases

delete   from employee a
where    rowid < (
select  max(rowid)
from    employee b
where   b.COL1 = a.COL1
and     b.COL2 = a.COL2
and     b.COL# = a.COL#);

sql, query

Thanks in advance!
Walter Anthony
System Administrator
National Electronic Attachment
Atlanta, Georgia 
1-800-782-5150 ext. 1608
 "If it's not broke....tweak it"

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removing duplicate recordswalt30 Jul
  • Re: removing duplicate recordsGerald Clark30 Jul
RE: removing duplicate recordsDavid Kramer30 Jul
  • Re: removing duplicate recordswalt31 Jul
    • Re: removing duplicate recordsVivian Wang31 Jul
    • RE: removing duplicate recordsGordon31 Jul
  • getting the maximum valuedestr031 Jul
  • Re: getting the maximum valueGerald Clark31 Jul
RE: removing duplicate recordsDavid Kramer31 Jul
RE: getting the maximum valueChris Kay31 Jul