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Theta join or equijoins??

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Theta join or equijoins?? Theta join or equijoins??

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Old 02-29-2008, 07:26 AM
JS
 
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Default Theta join or equijoins??
What is the definition of a theta join? I read that all joins with the
comparison operators:

=, <,> etc. are theta joins, but joins with = are called equijoins. How can
a theta join both be equijoin and a theta join?


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  #2 (permalink)  
Old 02-29-2008, 07:26 AM
David Portas
 
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Default Re: Theta join or equijoins??
In Relational Algebra a Theta Join is a join based on any of the binary
comparison operators (=, <, <=, >=, >, <>). An Equi-join is one example of a
Theta Join. There is no contradiction.

--
David Portas
SQL Server MVP
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