# SQL query problem **URL:** \ **Category:** Rails\ **Created:** [December 18, 2009, 6:17am UTC](https://www.ruby-forum.com/t/sql-query-problem/180351 "2009-12-18T06:17:49Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Learn\_by\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/e274bd/32.png) [@Learn\_by\_D](https://www.ruby-forum.com/u/Learn_by_D)\ **Post date:** [December 18, 2009, 6:17am UTC](https://www.ruby-forum.com/t/sql-query-problem/180351/1 "2009-12-18T06:17:49Z")
Please help me with finding a SQL select statement for the following problems. I have two classes: Site and Link Table Link has two columns: linking\_site\_id, and linked\_site\_id I would like to find all the links in table Link where linking\_site\_id = 3 or linked\_site\_id = 3 but only include a link where linked\_site\_id = 3 if the linking\_site\_id in that link is not one of the linked\_site\_id that site 3 links to. For example, if the Link table contains the following rows Linking\_site Linked\_site 2 1 3 2 3 4 5 3 2 3 What SQL select statement would return only the following: 3 2 3 4 5 3 If SQL query alone cannot do this, what is the most efficient way to do it via RoR? Thanks. Thanks. – You received this message because you are subscribed to the Google Groups “Ruby on Rails: Core” group. To post to this group, send email to removed\_email\_address@domain.invalid. To unsubscribe from this group, send email to removed\_email\_address@domain.invalid. For more options, visit this group at [http://groups.google.com/group/rubyonrails-core?hl=en](http://groups.google.com/group/rubyonrails-core?hl=en). ---
**Author:** ![Learn\_by\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/e274bd/32.png) [@Learn\_by\_D](https://www.ruby-forum.com/u/Learn_by_D)\ **Post date:** [December 18, 2009, 9:10am UTC](https://www.ruby-forum.com/t/sql-query-problem/180351/2 "2009-12-18T09:10:44Z")
Hi, Learn by Doing wrote: > Please help me with finding a SQL select statement for the following > problems. > Linking\_site Linked\_site > 2 1 > 3 2 > 3 4 > 5 3 > 2 3 > > What SQL select statement would return only the following: > > 3 2 > 3 4 > 5 3 TableName.find\_by\_sql(“select Linking\_site\_id, Linked\_site\_id from table t where Linking\_site\_id=3 or (Linked\_site\_id=3 and Linking\_site\_id in (select distinct(Linking\_site\_id) from table t2 where Linking\_site\_id=3 )”) Hope that helps 🙂 Regards, Salil G. ---
**Author:** ![Learn\_by\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/e274bd/32.png) [@Learn\_by\_D](https://www.ruby-forum.com/u/Learn_by_D)\ **Post date:** [December 21, 2009, 3:25pm UTC](https://www.ruby-forum.com/t/sql-query-problem/180351/3 "2009-12-21T15:25:30Z")
select \* from link\_table le where le.link\_site = ‘3’ or le.linked\_site =‘3’ and not exists (select 0 from link\_table li where li.link\_site = le.linked\_site and le.link\_site = li.linked\_site) 2009/12/18 Ease B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > linked\_site\_id that site 3 links to. For example, if the Link table – You received this message because you are subscribed to the Google Groups “Ruby on Rails: Talk” group. To post to this group, send email to removed\_email\_address@domain.invalid. To unsubscribe from this group, send email to removed\_email\_address@domain.invalid. For more options, visit this group at [http://groups.google.com/group/rubyonrails-talk?hl=en](http://groups.google.com/group/rubyonrails-talk?hl=en). ---
**Author:** ![Learn\_by\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/e274bd/32.png) [@Learn\_by\_D](https://www.ruby-forum.com/u/Learn_by_D)\ **Post date:** [December 21, 2009, 3:26pm UTC](https://www.ruby-forum.com/t/sql-query-problem/180351/4 "2009-12-21T15:26:05Z")
select \* from link\_table le where le.link\_site = ‘3’ or le.linked\_site =‘3’ and not exists (select 0 from link\_table li where li.link\_site = le.linked\_site and le.link\_site = li.linked\_site) 2009/12/18 Ease B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > linked\_site\_id that site 3 links to. For example, if the Link table – You received this message because you are subscribed to the Google Groups “Ruby on Rails: Talk” group. To post to this group, send email to removed\_email\_address@domain.invalid. To unsubscribe from this group, send email to removed\_email\_address@domain.invalid. For more options, visit this group at [http://groups.google.com/group/rubyonrails-talk?hl=en](http://groups.google.com/group/rubyonrails-talk?hl=en). ---
**Author:** ![Learn\_by\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/e274bd/32.png) [@Learn\_by\_D](https://www.ruby-forum.com/u/Learn_by_D)\ **Post date:** [December 30, 2009, 2:46am UTC](https://www.ruby-forum.com/t/sql-query-problem/180351/5 "2009-12-30T02:46:12Z")
Thanks everyone for your help! Happy New Year. On Dec 21, 6:24 am, Roberta [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > Please help me with finding a SQL select statement for the following > > contains the following rows > > 3 2 > > You received this message because you are subscribed to the Google G. > > “Ruby on Rails: Talk” group. > > To post to this group, send email to removed\_email\_address@domain.invalid. > > To unsubscribe from this group, send email to > > removed\_email\_address@domain.invalid[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > > . > > For more options, visit this group at > > [http://groups.google.com/group/rubyonrails-talk?hl=en](http://groups.google.com/group/rubyonrails-talk?hl=en). – You received this message because you are subscribed to the Google Groups “Ruby on Rails: Talk” group. To post to this group, send email to removed\_email\_address@domain.invalid. To unsubscribe from this group, send email to removed\_email\_address@domain.invalid. For more options, visit this group at [http://groups.google.com/group/rubyonrails-talk?hl=en](http://groups.google.com/group/rubyonrails-talk?hl=en).