The world rejoiced as ch@rodos.fzk.de (Christoph Haller) wrote:
>> 1. How to select duplicate records only from a single table using a
> select
>> query.
>>
> e.g.
> select sid,count(sid) from location group by sid having count(sid)>1;
>
> Do you get the idea?
> Your request is pretty unspecific, so if this is not what you're asking
> for,
> try again.
The aggregate is likely to perform horrifically badly. Here might
be an option:
Step 1. Find all of the duplicates...
select a.* into temp table sid from some_table a, some_table b where a.oid < b.oid and a.field1 = b.field1 and
a.field2= b.field2 and a.field3 = b.field3 and ... a.fieldn = b.fieldn;
Step 2. Look for the matching entries in the source table...
select a.* from some_table a, sid b where a.field1 = b.field1 and a.field2 = b.field2 and a.field3 = b.field3 and
... a.fieldn = b.fieldn;
[There's a weakness here; if there are multiple dupes, they may get
picked multiple times in the second query :-(.]
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