JOIN vs. LEFT JOIN

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От Nico Callewaert
Тема JOIN vs. LEFT JOIN
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Msg-id DD54522572014D84A247B4662D5620AD@etsinformatics.local
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Ответы Re: JOIN vs. LEFT JOIN  (Andreas Wenk <a.wenk@netzmeister-st-pauli.de>)
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Hi !
 
I heard that it is always better to use a full JOIN rather than a LEFT JOIN, for performance reasons.  Is that correct ?
But it's barely possible to use full JOINS all the time, since most of the lookup fields are not required.
Example : in the customer table, the customer type is a looup field to a customer_type table.  But that is not required to post the record.  So I was thinking to create a record in the customer_type table with ID = -1.  And in case the customer type is NULL, to assign it the value -1.  That way, it will be always possible to do a full JOIN.  I was wondering if that is good practice or rather nonsense ?
 
Many thanks in advance,
Nico

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