List:General Discussion« Previous MessageNext Message »
From:Perry Merritt Date:April 21 2005 3:36am
Subject:many to many
View as plain text  
Hi, I'm a novice.
 
I've designed a database that supports many to many relationships (actually many to many
to many) and I need help creating the query to find my data. I know things like JOINs
exist, but don't have a clue how to use them.
 
I have three main tables and two link tables, The main tables are A, B, and C. Each are
defined with id INT and word VARCHAR(32); The link tables are X and Y. X links A and B
with the columns a_id and b_id. Y links the tables B and C with columns b_id and c_id.
 
Here's what I want to accomplish:
 
  Get the A.id where A.word = "some value"
  Use A.id to search X where X.a_id=A.id (from above)
   Use all occurences of X.a_id = A.id to select word from B using B.id=X.b_id
   AND finally,
   select C.id where C.Word = "Some other value"
    and given Y.c_id = C.id use the matching Y.b_id to further limit the select on B.word
 
Can this convoluted mess be understood and if so, can a single query pull it off?
 
I'm implementing this in perl, so I can break the queries into pieces if I absolutely have
to.
 
Thanks



__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com 
Thread
many to manyPerry Merritt21 Apr
  • Re: many to manyKim Briggs21 Apr
  • Re: many to manySimon Garner21 Apr
  • Re: many to manyRhino21 Apr