How can I remove a duplicate row?

I have a table that has two rows in it that are identical and need to
delete one of them. Since any kind of where clause in a delete
statement will hit both of them, how can I remove one of these rows?
TIAPick the dups by grouping and put them in a temp table. remove all
duplicate records from the parent table and insert the groped
duplicates (in this table, you should have one occourance of each
record) from the temp table into this old table that dosent have any
rows of these duplicate records.
Hope I didnt loose you with my wording.. ..! (It would help if you had
given some DDL code...!|||http://www.aspfaq.com/2431
Now how about having a key and/or other constraints to prevent this from
happening again?
http://www.aspfaq.com/2509
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"Matthew Speed" <mspeed@.mspeed.net> wrote in message
news:7pgav09liocekdk7rdgd2leo1gnuct58n3@.4ax.com...
> I have a table that has two rows in it that are identical and need to
> delete one of them. Since any kind of where clause in a delete
> statement will hit both of them, how can I remove one of these rows?
> TIA|||On 24 Jan 2005 11:08:44 -0800, "QueryBuilder" <pg.242w@.gmail.com>
wrote:
>Pick the dups by grouping and put them in a temp table. remove all
>duplicate records from the parent table and insert the groped
>duplicates (in this table, you should have one occourance of each
>record) from the temp table into this old table that dosent have any
>rows of these duplicate records.
>Hope I didnt loose you with my wording.. ..! (It would help if you had
>given some DDL code...!
This makes sense. I was hoping I could remove the extra in place. (My
thinking is that if the DB knows there are two rows there must be
someway that it uniquely identifies them.)|||Matthew Speed <mspeed@.mspeed.net> wrote in
news:7pgav09liocekdk7rdgd2leo1gnuct58n3@.4ax.com:
> I have a table that has two rows in it that are identical and need to
> delete one of them. Since any kind of where clause in a delete
> statement will hit both of them, how can I remove one of these rows?
> TIA
set rowcount 1
delete from t1
where col1=1 and col2=1|||On Mon, 24 Jan 2005 14:08:04 -0500, "Aaron [SQL Server MVP]"
<ten.xoc@.dnartreb.noraa> wrote:
>http://www.aspfaq.com/2431
>Now how about having a key and/or other constraints to prevent this from
>happening again?
The keys are now in place. This was a client database I was hired to
do some work on. When I saw the problem my first thought was to add
constraints but one can't implement a unique constraint unless the
existing data is already unique.
>http://www.aspfaq.com/2509|||"Matthew Speed" <mspeed@.mspeed.net> wrote in message
news:cjmav0dg4s0uki574285s1rekljfod4lfa@.4ax.com...
> On Mon, 24 Jan 2005 14:08:04 -0500, "Aaron [SQL Server MVP]"
> <ten.xoc@.dnartreb.noraa> wrote:
> >http://www.aspfaq.com/2431
> >
> >Now how about having a key and/or other constraints to prevent this
from
> >happening again?
> The keys are now in place. This was a client database I was hired
to
> do some work on. When I saw the problem my first thought was to add
> constraints but one can't implement a unique constraint unless the
> existing data is already unique.
I add identitiy columns to tables all the time to get rid of dups. You
can leave the identitiy column around or simply remove it after you
are done. Another technique is to create a new table as select
distinct * from xxx, drop the old one and rename the new one as
appropriately.|||> I add identitiy columns to tables all the time to get rid of dups.
With sensible design, you won't have dupes at all. Does your data not have
a candidate key? Do you not use primary keys for any reason?|||"Aaron [SQL Server MVP]" <ten.xoc@.dnartreb.noraa> wrote in message
news:uVkkXtmAFHA.2792@.TK2MSFTNGP15.phx.gbl...
> > I add identitiy columns to tables all the time to get rid of dups.
> With sensible design, you won't have dupes at all. Does your data
not have
> a candidate key? Do you not use primary keys for any reason?
Data is often loaded in a database before being transformed and
duplicates removed. This is what happens in the real world.|||> Data is often loaded in a database before being transformed and
> duplicates removed. This is what happens in the real world.
The real world? What is that? Glad my job is inside a vacuum, where we
load data into a staging table, insert the NEW, NON-DUPLICATE rows into our
production tables, then blow away or archive the staging data. (Rather than
just throwing everything into our production tables, and removing duplicates
there.)|||"Aaron [SQL Server MVP]" <ten.xoc@.dnartreb.noraa> wrote in message
news:uHq19RnAFHA.2572@.TK2MSFTNGP10.phx.gbl...
> > Data is often loaded in a database before being transformed and
> > duplicates removed. This is what happens in the real world.
> The real world? What is that? Glad my job is inside a vacuum,
where we
> load data into a staging table
Now, think about your "staging" table and the tables I am talking
about. Is the light coming on yet?|||> Now, think about your "staging" table and the tables I am talking
> about. Is the light coming on yet?
Funny that you removed the rest of my description, which kind of usurps your
petty insult. Grow up.|||"Aaron [SQL Server MVP]" <ten.xoc@.dnartreb.noraa> wrote in message
news:eBY9JUoAFHA.1404@.TK2MSFTNGP11.phx.gbl...
> > Now, think about your "staging" table and the tables I am talking
> > about. Is the light coming on yet?
> Funny that you removed the rest of my description, which kind of
usurps your
> petty insult. Grow up.
Sorry if I struck a nerve. I only responded to your post in the same
"tone" that was directed at me. Concerning the part of your post that
was redacted it was simply irrelevant. If you still don't get it I'm
not sure I can dumb it down any further. Sorry :(
--== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==--
http://www.newsfeeds.com The #1 Newsgroup Service in the World! >100,000 Newsgroups
--= East/West-Coast Server Farms - Total Privacy via Encryption =--|||> was redacted it was simply irrelevant. If you still don't get it I'm
> not sure I can dumb it down any further. Sorry :(
Oh christ. You know what everybody? I am sick and tired of helping people
to end up dealing with this childish crap. I have better things to do with
my time than to be at the wrong end of someone's childish recess attacks.
See ya.|||"Aaron [SQL Server MVP]" <ten.xoc@.dnartreb.noraa> wrote in message
news:ebL2Z7oAFHA.1400@.TK2MSFTNGP11.phx.gbl...
> > was redacted it was simply irrelevant. If you still don't get it
I'm
> > not sure I can dumb it down any further. Sorry :(
> Oh christ. You know what everybody? I am sick and tired of helping
people
> to end up dealing with this childish crap. I have better things to
do with
> my time than to be at the wrong end of someone's childish recess
attacks.
> See ya.
You're actually trying to help?
Here's some helpful advice.
If you're going to post with this attitude of condescension, at least
get your facts right. You might consider thinking a bit more about the
questions and replys before posting. You also seem to enjoy putting
people on the defensive and when you can't get your way you end up
lashing out like a child.
I'll let you get you the last word in since you seem intent on
"helping" me until I give up.|||/*select duplicate rows
select count(trnno), trnno from dw_ndls_train
group by trnno
having count(trnno) > 1
/*del duplicate rows
delete from dw_ndls_train
where (trnno, trname)
not in
( select min(trnno), trname
from dw_ndls_train group by trname
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