Subject Re: [firebird-support] Delete duplicates
Author Bart Bakker
Clay Shannon wrote:
> Anybody have a SQL example for deleting duplicate records in a table
> (deleting all but one)?
> Or better yet, one that deletes redundant records that have certain column
> values in common, regardless of the values in all other columns? E.g., if
> Client_ID, firstname, middlename, lastname are the same, regardless of what
> may be in address, city, state, zip, etc. fields, delete the dupes?
You can try something like:

delete from redundant_table deltable
where deltable.ID in (
select seltable.ID from redundant_table seltable
where (seltable.ID <> deltable.ID) and
(seltable.Client_ID = deltable.Client_ID) and

You have to make sure that your table has a unique identifier per record
(called ID in the example) otherwise you don't have a reference to the
current record.

With kind regards,

Bart Bakker
Senior Software Engineer
e: bart@...
t: +31 (0)20 581 19 75
f: +31 (0)20 581 19 70
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