Solved

MySQL query with multiple joins on 7 tables

Posted on 2008-10-29
3
199 Views
Last Modified: 2011-10-19
Hello,

I need help with a query involving 7 tables. I've attached a visual schema that I hope will help.
What I want to do is select all of the documents and display their associated data in each table.

1. Show all the fields in all the records in docs
2. Match docs.doc_cat->category.cat_id to show the cat_name field in category
3. Match docs.doc_origin->origin.origin_id to show the origin field in origin
4. Match docs.doc_id=mapchapters.doc_id AND chapters.chapter_id=mapchapters.chapid to show the chapter field in the chapters table
5. Match docs.doc_id=mapcriteria.doc_id AND criteria.criteria_id=map_criteria.criteria_id to show the criteria field in the criteria table

I was doing fine joning the origin, docs, and category tables,

but when it came to steps 4 and 5 I hit a wall.

each document has 1 category and 1 origin but many criteria and many chapters
document->chapters=many:many
document->criteria=many:many

I hope that I have provided all of the information needed to answer this query, but if not please let me know and I will get back to you right away.
Thanks,
Audg
SELECT * FROM docs AS d1,
LEFT JOIN category AS c1 ON d1.doc_cat=c1.cat_id 
LEFT JOIN origin AS o1 ON d1.doc_origin=o1.origin_id

Open in new window

archiveschema.jpg
0
Comment
Question by:aberns
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
3 Comments
 
LVL 32

Accepted Solution

by:
Daniel Wilson earned 500 total points
ID: 22834349
You were on the right track ... I think this is your answer.

SELECT d1.*, c1.cat_name, o1.origin, ch.chapter,  cr.criteria
FROM docs AS d1
LEFT JOIN category AS c1 ON d1.doc_cat=c1.cat_id 
LEFT JOIN origin AS o1 ON d1.doc_origin=o1.origin_id
Left Join mapchapters mc on d1.doc_id = mc.doc_id
Left Join chapters ch on mc.chapter_id = ch.chapter_id
left join map_criteria mcr on d1.doc_id = mcr.doc_id
left join criteria cr on cr.criteria_id = mcr.criteria_id

Open in new window

0
 

Author Comment

by:aberns
ID: 22835666
Awesome! It worked! Thanks. I kept thinking I had to define docs with different aliases since I was joining it to multiple tables. Also, is the AS optional? i.e. you have
Join mapchapters mc
but
Join origin AS 01
0
 
LVL 32

Expert Comment

by:Daniel Wilson
ID: 22835699
Yes, I'm pretty sure AS is optional.  I know it is in MS SQL Server ...
0

Featured Post

What is SQL Server and how does it work?

The purpose of this paper is to provide you background on SQL Server. It’s your self-study guide for learning fundamentals. It includes both the history of SQL and its technical basics. Concepts and definitions will form the solid foundation of your future DBA expertise.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

When table data gets too large to manage or queries take too long to execute the solution is often to buy bigger hardware or assign more CPUs and memory resources to the machine to solve the problem. However, the best, cheapest and most effective so…
In part one, we reviewed the prerequisites required for installing SQL Server vNext. In this part we will explore how to install Microsoft's SQL Server on Ubuntu 16.04.
Polish reports in Access so they look terrific. Take yourself to another level. Equations, Back Color, Alternate Back Color. Write easy VBA Code. Tighten space to use less pages. Launch report from a menu, considering criteria only when it is filled…
This is a high-level webinar that covers the history of enterprise open source database use. It addresses both the advantages companies see in using open source database technologies, as well as the fears and reservations they might have. In this…

705 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question