Re: Compare Tablets by Key1 and Remove Duplicates

[Cal Evans <suppressed>]

Subqueries.

select * from ClientJune2005 where customerCode = (select customercode 
from ClientAug2005);

http://dev.mysql.com/doc/refman/4.1/en/subqueries.html

=C=
|
| Cal Evans
| http://www.calevans.com
|

VaioLord wrote:
> I have just moved over to a new job and been given the task of trying to 
> sort out historic client databases (MS-Access).  I have exported 
> everything to CSV, then into MySQL 5.0.15 no problems at all.  However 
> due to the way the original system was developed i have so much 
> duplicated data it is crazy.
>
> Can anyone point me in the right direction for a method to delete 
> records based on a a field value if it also exists in another table.
>
> ie.
>
> Table "ClientJun2005" contains fields "customercode", "name", "address", 
>  "telephone", with the field "customercode" being the Unique Primary Key.
>
> Table "ClientAug2005" contains fields "customercode", "name", "address", 
>  "telephone", with the field "customercode" being the Unique Primary Key.
>
> What I need is to compare tables "ClientJun2005" and "ClientAug2005" by 
> "customercode" when the this value exists in both databases delete one 
> and leave one alone.
>
> I know that it would be possible to do this with PHP but home that there 
> is a simple MySQL method I can run direct of MySQL.
>
> Hope someone can help me out.
>
> Stephen

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