Re: SELECT duplicates in a table

Assuming identification_number is a unique (primary) key...

select * from my_table where date_of_birth  in (select date_of_birth
from my_table group by date_of_birth having count(*) > 1)

Or - it may be quicker to do...

select * from my_table a where exists (select 'x'  from my_table b where
a.date_of_birth = b.date_of_birth group by b.date_of_birth having
count(*) > 1)


Kall, Bruce A. wrote:

> I've look for a solution to this, but have only been able to find
> solutions to delete duplicate entries in a table by deleting entries
> not returned by SELECT DISTINCT.
>
> What sql should I use to SELECT entries in a table that have two
> particular column values that match?
>
> For example, my_table has
> name, phone number, identification_number, zip code, date of birth,
> and city
>
> I want to SELECT rows from this table that have the same values in
> identification and date of birth (duplicates) so I can have the user
> look at them in order to figure out which one to delete.
>
> I tried something like:
>
>  $db_sql = "SELECT * FROM my_table GROUP BY identification_number
> HAVING count(date_of_birth) > 1 ORDER BY name"
>
> but that doesn't seem to work.
>
> Thanks,
> Bruce
>
>
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