Comments on: Back to basics: Equi and non-equijoins http://awads.net/wp/2006/04/26/back-to-basics-equi-and-non-equijoins/ News, views, tips and tricks on Oracle and other fun stuff Thu, 07 Aug 2008 23:46:38 +0000 http://wordpress.org/?v=2.5 By: Gints Plivna http://awads.net/wp/2006/04/26/back-to-basics-equi-and-non-equijoins/#comment-52034 Gints Plivna Mon, 17 Mar 2008 15:13:32 +0000 http://awads.net/wp/2006/04/26/back-to-basics-equi-and-non-equijoins/#comment-52034 Equi joins and inner joins are terms using different classification methods. Just like one can classify movies awarded by Oscars or not and by movie duration time. Whether movie is awarded with Oscar has nothing to do with movie duration time and vice versa. I've tried to show the classification of joins using ER meta model here: http://gplivna.blogspot.com/2008/01/sql-join-types-im-studying-bit-sql.html Equi joins and inner joins are terms using different classification methods. Just like one can classify movies awarded by Oscars or not and by movie duration time. Whether movie is awarded with Oscar has nothing to do with movie duration time and vice versa. I’ve tried to show the classification of joins using ER meta model here: http://gplivna.blogspot.com/2008/01/sql-join-types-im-studying-bit-sql.html

]]> By: sreenivasulu http://awads.net/wp/2006/04/26/back-to-basics-equi-and-non-equijoins/#comment-51669 sreenivasulu Thu, 11 Oct 2007 06:47:53 +0000 http://awads.net/wp/2006/04/26/back-to-basics-equi-and-non-equijoins/#comment-51669 <p>What is the difference between Equi and Inner Joins?</p> What is the difference between Equi and Inner Joins?

]]> By: poonam http://awads.net/wp/2006/04/26/back-to-basics-equi-and-non-equijoins/#comment-50752 poonam Thu, 10 May 2007 11:46:49 +0000 http://awads.net/wp/2006/04/26/back-to-basics-equi-and-non-equijoins/#comment-50752 <p>Hi Eddie, Will you please tell about <> or != operator, does that make an equi join or non equi join?</p> Hi Eddie, Will you please tell about <> or != operator, does that make an equi join or non equi join?

]]> By: Eddie Awad http://awads.net/wp/2006/04/26/back-to-basics-equi-and-non-equijoins/#comment-50739 Eddie Awad Thu, 03 May 2007 06:17:58 +0000 http://awads.net/wp/2006/04/26/back-to-basics-equi-and-non-equijoins/#comment-50739 <p>Don, I see your point. But, strictly following the definition of the equi-join which says that it "is a join with a join condition containing an <em>equality</em> operator", I still think that it is not an equi-join (unless IN is an equality operator).</p> Don, I see your point. But, strictly following the definition of the equi-join which says that it “is a join with a join condition containing an equality operator”, I still think that it is not an equi-join (unless IN is an equality operator).

]]> By: Don Seiler http://awads.net/wp/2006/04/26/back-to-basics-equi-and-non-equijoins/#comment-50736 Don Seiler Wed, 02 May 2007 20:35:29 +0000 http://awads.net/wp/2006/04/26/back-to-basics-equi-and-non-equijoins/#comment-50736 <p>So if you used the IN clause it is a non-equijoin, but if you rewrote it as multiple equality statements separated by OR, it IS and equijoin?</p> <p>My first opinion would definitely be to refer to IN as an equijoin.</p> So if you used the IN clause it is a non-equijoin, but if you rewrote it as multiple equality statements separated by OR, it IS and equijoin?

My first opinion would definitely be to refer to IN as an equijoin.

]]> By: Eddie Awad http://awads.net/wp/2006/04/26/back-to-basics-equi-and-non-equijoins/#comment-5025 Eddie Awad Thu, 27 Apr 2006 18:53:42 +0000 http://awads.net/wp/2006/04/26/back-to-basics-equi-and-non-equijoins/#comment-5025 <p>Good question Vladimir. For example, is the following query an equijoin?</p> <pre> SELECT e.first_name, d.department_name FROM employees e INNER JOIN departments d ON e.department_id IN (d.department_id, 9999) </pre> <p>An equijoin is a join with a join condition containing an equality operator. Since the above query does not have the equality operator (=) in the join condition, that makes it a non-equijoin.</p> Good question Vladimir. For example, is the following query an equijoin?

SELECT e.first_name,
       d.department_name
  FROM employees e INNER JOIN departments d
       ON e.department_id IN (d.department_id, 9999)

An equijoin is a join with a join condition containing an equality operator. Since the above query does not have the equality operator (=) in the join condition, that makes it a non-equijoin.

]]> By: Vladimir Chursin http://awads.net/wp/2006/04/26/back-to-basics-equi-and-non-equijoins/#comment-4975 Vladimir Chursin Thu, 27 Apr 2006 08:40:06 +0000 http://awads.net/wp/2006/04/26/back-to-basics-equi-and-non-equijoins/#comment-4975 <p>Hi, Addie I've been thinking about equi-joins. What if we have an IN clause? Will it be an equi or nonequijoin? Thanks.</p> Hi, Addie
I’ve been thinking about equi-joins.
What if we have an IN clause? Will it be an equi or nonequijoin?
Thanks.

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