Comments on: Creating Recursive SQL Calls for Tables with Parent-Child Relationships http://www.webinade.com/web-development/creating-recursive-sql-calls-for-tables-with-parent-child-relationships Freshly Squeezed Wed, 20 Aug 2008 13:58:53 +0000 http://wordpress.org/?v=2.2.3 By: Mark http://www.webinade.com/web-development/creating-recursive-sql-calls-for-tables-with-parent-child-relationships#comment-1502 Mark Thu, 07 Aug 2008 00:31:26 +0000 http://www.webinade.com/web-development/creating-recursive-sql-calls-for-tables-with-parent-child-relationships#comment-1502 Thank you for sharing this. I had a similar issue looking at categories of various levels (category-subcate-subsubcate .. etc), and your script helped tremendously. One thing I'd like to point out though, from following your code, is that you missed a space in "ALLSELECT" (making it "ALL SELECT"). Me with my entry level sql knowledge thought it was some secret keyword I've never came across. ;) Thank you for sharing this. I had a similar issue looking at categories of various levels (category-subcate-subsubcate .. etc), and your script helped tremendously. One thing I’d like to point out though, from following your code, is that you missed a space in “ALLSELECT” (making it “ALL SELECT”). Me with my entry level sql knowledge thought it was some secret keyword I’ve never came across. ;)

]]> By: Uma http://www.webinade.com/web-development/creating-recursive-sql-calls-for-tables-with-parent-child-relationships#comment-926 Uma Thu, 22 May 2008 16:52:17 +0000 http://www.webinade.com/web-development/creating-recursive-sql-calls-for-tables-with-parent-child-relationships#comment-926 very interesting article. wish i had known this earlier, would have saved me a lot of trouble. but knowing it now with such a clear explanation is very much worth appreciating the author. very interesting article. wish i had known this earlier, would have saved me a lot of trouble. but knowing it now with such a clear explanation is very much worth appreciating the author.

]]> By: GJL http://www.webinade.com/web-development/creating-recursive-sql-calls-for-tables-with-parent-child-relationships#comment-923 GJL Wed, 21 May 2008 19:45:51 +0000 http://www.webinade.com/web-development/creating-recursive-sql-calls-for-tables-with-parent-child-relationships#comment-923 Thanks! I never knew that this method existed. It has saved me a lot of time. Thanks! I never knew that this method existed. It has saved me a lot of time.

]]> By: Glen http://www.webinade.com/web-development/creating-recursive-sql-calls-for-tables-with-parent-child-relationships#comment-805 Glen Mon, 07 Apr 2008 18:06:58 +0000 http://www.webinade.com/web-development/creating-recursive-sql-calls-for-tables-with-parent-child-relationships#comment-805 Thank you for this! I used your example to replace a cursor method I was using and it cut the query response time to about half. Very nice article! - Glen Thank you for this! I used your example to replace a cursor method I was using and it cut the query response time to about half.

Very nice article!

- Glen

]]> By: Time Employee Equivalent http://www.webinade.com/web-development/creating-recursive-sql-calls-for-tables-with-parent-child-relationships#comment-278 Time Employee Equivalent Sat, 09 Feb 2008 22:11:37 +0000 http://www.webinade.com/web-development/creating-recursive-sql-calls-for-tables-with-parent-child-relationships#comment-278 <strong>Do you want to know if your employees are working or are wasting time?...</strong> In our days productivity has become the God of industry, so all employers expect employees to work faster, work smarter and work more.... Do you want to know if your employees are working or are wasting time?…

In our days productivity has become the God of industry, so all employers expect employees to work faster, work smarter and work more….

]]> By: Sean http://www.webinade.com/web-development/creating-recursive-sql-calls-for-tables-with-parent-child-relationships#comment-75 Sean Sat, 01 Dec 2007 04:09:48 +0000 http://www.webinade.com/web-development/creating-recursive-sql-calls-for-tables-with-parent-child-relationships#comment-75 Would a 'connect by' statement work here? select employee, subordinate, level from orgChart start with employee = 'Frank' connect by subordinate = prior employee If I'm not mistaken, this would produce a list of employees who report to Frank. 'level' in this case would produce an incremented number based on the 'level' below Frank. I'm a little confused by the implied schema of the orgChart. I think it would be better if each employee record held a reference to the supervisor, but whatever. Would a ‘connect by’ statement work here?

select employee, subordinate, level
from orgChart
start with employee = ‘Frank’
connect by subordinate = prior employee

If I’m not mistaken, this would produce a list of employees who report to Frank. ‘level’ in this case would produce an incremented number based on the ‘level’ below Frank.

I’m a little confused by the implied schema of the orgChart. I think it would be better if each employee record held a reference to the supervisor, but whatever.

]]> By: Juan http://www.webinade.com/web-development/creating-recursive-sql-calls-for-tables-with-parent-child-relationships#comment-17 Juan Wed, 10 Oct 2007 13:23:40 +0000 http://www.webinade.com/web-development/creating-recursive-sql-calls-for-tables-with-parent-child-relationships#comment-17 I understand how MPTT can be used for easy retrieval from a tree. However, am I missing something, or will every change (insert/delete/move) to a tree mean that the right/left values of every node in the tree may need to be rebuilt? It seems to me that any time the tree changes, you have to do a recursive traversal to rebuild the MPTT indices, and only after that could you take advantage of MPTT's easy retrieval. Of course in some situations it's a worthwhile tradeoff - I just want to make sure I'm characterizing this correctly. Thanks, -Juan I understand how MPTT can be used for easy retrieval from a tree. However, am I missing something, or will every change (insert/delete/move) to a tree mean that the right/left values of every node in the tree may need to be rebuilt? It seems to me that any time the tree changes, you have to do a recursive traversal to rebuild the MPTT indices, and only after that could you take advantage of MPTT’s easy retrieval. Of course in some situations it’s a worthwhile tradeoff - I just want to make sure I’m characterizing this correctly. Thanks, -Juan

]]> By: links for 2007-10-01 « D e j a m e S e r http://www.webinade.com/web-development/creating-recursive-sql-calls-for-tables-with-parent-child-relationships#comment-10 links for 2007-10-01 « D e j a m e S e r Mon, 01 Oct 2007 15:18:50 +0000 http://www.webinade.com/web-development/creating-recursive-sql-calls-for-tables-with-parent-child-relationships#comment-10 [...] Creating Recursive SQL Calls for Tables with Parent-Child Relationships at Webinade (tags: sql) [...] […] Creating Recursive SQL Calls for Tables with Parent-Child Relationships at Webinade (tags: sql) […]

]]> By: David http://www.webinade.com/web-development/creating-recursive-sql-calls-for-tables-with-parent-child-relationships#comment-9 David Sun, 30 Sep 2007 23:17:40 +0000 http://www.webinade.com/web-development/creating-recursive-sql-calls-for-tables-with-parent-child-relationships#comment-9 I guess this works, but a much cleaner, clearer and efficient way to achieve this is to use an MPTT (modified pre-order tree traversal) table. It employs the use of a 'left' and 'right' value for each node in the tree, and with one sql query (no temporary views/tables) you can get the complete (and ordered) list of all children, or if you know the child and want all parents, you can get a breadcrumb trail back up the tree as well with one query. Work smart, not hard :) I guess this works, but a much cleaner, clearer and efficient way to achieve this is to use an MPTT (modified pre-order tree traversal) table. It employs the use of a ‘left’ and ‘right’ value for each node in the tree, and with one sql query (no temporary views/tables) you can get the complete (and ordered) list of all children, or if you know the child and want all parents, you can get a breadcrumb trail back up the tree as well with one query. Work smart, not hard :)

]]> By: Roman Mackovcak http://www.webinade.com/web-development/creating-recursive-sql-calls-for-tables-with-parent-child-relationships#comment-8 Roman Mackovcak Sun, 30 Sep 2007 22:29:37 +0000 http://www.webinade.com/web-development/creating-recursive-sql-calls-for-tables-with-parent-child-relationships#comment-8 I would prefer using nested sets. There should be libraries for your language. I would prefer using nested sets. There should be libraries for your language.

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