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Message Posted: Thu, 19 Jan 2006 @ 09:50:25 GMT


     
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Subj:   Differences between queries
 
From:   Vijay R. K.

Hello learned people,

I have 2 sets of questions.

1) I wanted to know what the differences between he following are and their uses

a)Cross join

b)Product join

c)Cartesian product


Are (a) and (c) the same? Are there any specific instances where I would want to use any of these consciously? All the while, I've been reading that these are accidental.


2) What is the difference between the two queries below? I see that Teradata makes the LOJ an equi join when I use a WHERE instead of an 'AND'

     Sel a.col1, b.col2
     FROM sales_order a
     LEFT OUTER JOIN order_line_ b
     ON a.order_header_id = b.header_id
     AND a.security_country_code = b.security_country_code;
     AND a.order_line_id IS NULL

     Sel a.col1, b.col2
     FROM sales_order a
     LEFT OUTER JOIN order_line_ b
     ON a.order_header_id = b.header_id
     AND a.sr_code = b.sr_code;
     WHERE a.order_line_id IS NULL

Please advice.


Thanks and Regards

VRK



     
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