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From:Peter Brawley Date:October 4 2005 7:23pm
Subject:Re: deleting unwanted rows
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Merlin,

Ouch, brain cramp, make that...

 SELECT id
 FROM table1
 LEFT JOIN table2 ON table1.id=table2.table1_id
 WHERE table2.table1_id IS NULL;

PB

-----

Merlin wrote:

> Hi there,
>
> I just discovered, that I do have some old rows I do not need anymore. 
> A result from forgeting to empty the table before starting to go into 
> production :-)
> However, I do try to find the rows which are not asociated with 
> another table in order to delete them.
> I have 2 tables:
> table1 and table2
>
> table1 has the key: "ID"
> table2 has the subkey "table1_id"
>
> Now I would like to delete all rows in table1 which are not listed in 
> table2 with an id.
> I tried:
> SELECT
>    t1.*
> FROM
>    table1 as t1,
>    table2 as t2
> WHERE
>    t1.ID != t2.table1_id
>
> But this returns hundreds of thousends of results.
> I also tryed to group by t1.ID, but it did not help
>
> Does anybody have a good idea how to get rid of those rows?
>
> Thanx, Merlin
>
> PS: Thanx for the answer for the question with full text search! That 
> worked excellent!
>


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Thread
deleting unwanted rowsMerlin4 Oct
  • Re: deleting unwanted rowsSGreen4 Oct
  • Re: deleting unwanted rowsPeter Brawley4 Oct
  • Re: deleting unwanted rowsPeter Brawley4 Oct
Re: deleting unwanted rowsSGreen4 Oct
  • Re: deleting unwanted rowsMerlin5 Oct