473,322 Members | 1,425 Online
Bytes | Software Development & Data Engineering Community
Post Job

Home Posts Topics Members FAQ

Join Bytes to post your question to a community of 473,322 software developers and data experts.

Finding lookup fields in MySQL

I've got a lookup table for a lookup table and can't work out the SQL to
do a search. Can anyone help?

As an example, consider the following:

Table 1 - books:
fields: book_id, price, title, author
data:
1, 2.99, 'Life', 'A. Slug'
2, 4.99, 'The Universe', 'A. Planet'

Table 2 - book_fields:
fields: field_id, field_name
data:
1, 'cover_colour'
2, 'cover_type'

Table 3 - book_field_lookup:
data: book_id, field_id, field_value
1, 1, 'blue'
1, 2, 'hardback'
2, 1, 'blue'
2, 2, 'softback'
How do I do all hardback books that are blue? I'm sure that the answer
is simple, but have a block today :(

--
Rob Allen
Jul 16 '05 #1
4 6373
In message <Mz**************@rob.mustardhouse.com>, Rob Allen
<ro***@the-allens.net> writes
How do I do all hardback books that are blue? I'm sure that the answer
is simple, but have a block today :(


Umm.. That should be "How do I find all the hardback books that are
blue?"

--
Rob Allen
Jul 16 '05 #2
so do you need the sql?

something like

select * from table1, table3 where table1.bood_id = table3.book_id and
table3.field_value like "%hardback%';
"Rob Allen" <ro***@the-allens.net> wrote in message
news:Mz**************@rob.mustardhouse.com...
I've got a lookup table for a lookup table and can't work out the SQL to
do a search. Can anyone help?

As an example, consider the following:

Table 1 - books:
fields: book_id, price, title, author
data:
1, 2.99, 'Life', 'A. Slug'
2, 4.99, 'The Universe', 'A. Planet'

Table 2 - book_fields:
fields: field_id, field_name
data:
1, 'cover_colour'
2, 'cover_type'

Table 3 - book_field_lookup:
data: book_id, field_id, field_value
1, 1, 'blue'
1, 2, 'hardback'
2, 1, 'blue'
2, 2, 'softback'
How do I do all hardback books that are blue? I'm sure that the answer
is simple, but have a block today :(

--
Rob Allen

Jul 16 '05 #3
On Mon, 11 Aug 2003 12:35:55 +0000 (UTC), Rob Allen <ro***@the-allens.net>
wrote:
I've got a lookup table for a lookup table and can't work out the SQL to
do a search. Can anyone help?

As an example, consider the following:

Table 1 - books:
fields: book_id, price, title, author
data:
1, 2.99, 'Life', 'A. Slug'
2, 4.99, 'The Universe', 'A. Planet'

Table 2 - book_fields:
fields: field_id, field_name
data:
1, 'cover_colour'
2, 'cover_type'

Table 3 - book_field_lookup:
data: book_id, field_id, field_value
1, 1, 'blue'
1, 2, 'hardback'
2, 1, 'blue'
2, 2, 'softback'
How do I do all hardback books that are blue? I'm sure that the answer
is simple, but have a block today :(


Join to your books table with your field tables twice, once for type, once for
colour, something like:

SELECT b.book_id
FROM books b,
book_fields bf_colour, book_field_lookup bfl_colour,
book_fields bf_type, book_field_lookup bfl_type
WHERE bf_colour.field_name = 'cover_colour'
AND bf_colour.field_id = bfl_colour.field_id
AND bfl_colour.field_value = 'blue'
AND bfl_colour.book_id = b.book_id
AND bf_type.field_name = 'cover_type'
AND bf_type.field_id = bfl_type.field_id
AND bfl_type.field_value = 'hardback'
AND bfl_type.book_id = b.book_id

--
Andy Hassall (an**@andyh.co.uk) icq(5747695) (http://www.andyh.co.uk)
Space: disk usage analysis tool (http://www.andyhsoftware.co.uk/space)
Jul 16 '05 #4
In message <28********************************@4ax.com>, Andy Hassall
<an**@andyh.co.uk> writes

Join to your books table with your field tables twice, once for type,
once for colour, something like:

Ah... You can multiply join the same table! So for N search criteria, I
need to join N times...

Thanks !

--
Rob Allen
Jul 16 '05 #5

This thread has been closed and replies have been disabled. Please start a new discussion.

Similar topics

2
by: Eric Linders | last post by:
Hi everyone. :-) Our site gets a ton of traffic on our contact forms, which collect the standard information (name, address, city, state, zip, home phone, etc.) The form validation is done with...
4
by: Aaron W. West | last post by:
Timings... sometimes there are almost too many ways to do the same thing. The only significant findings I see from all the below timings is: 1) Integer math is generally fastest, naturally....
3
by: my-wings | last post by:
I've been reading about how evil Lookup fields in tables are, but I've got to be missing something really basic. I know this subject has been covered before, because I've just spent an hour or two...
1
by: Zachary Turner | last post by:
I want to make a Lookup Field based on another Lookup field. In other words, I have this table A with two fields: ID and Name, where ID is an Autonumber and Name is a friendly name. Then I have a...
3
by: google | last post by:
I have a database with four table. In one of the tables, I use about five lookup fields to get populate their dropdown list. I have read that lookup fields are really bad and may cause problems...
4
by: jon f kaminsky | last post by:
Hi- I've seen this problem discussed a jillion times but I cannot seem to implement any advice that makes it work. I am porting a large project from VB6 to .NET. The issue is using the combo box...
2
by: Lance Williams | last post by:
How can you programatically tell if a field in a table is a lookup field? I am looping through the fields collection and I want to see if any fields are lookup fields. Is there a property, or...
3
by: Markw | last post by:
I think this was recently asked but I was a little lost on the example that was used so I'm reasking it with an example I can understand. Also forgive me for such a basic question but I really am...
7
by: samdev | last post by:
I have set up a table with a few fields that are set to required....all work fine except the fields that are Lookup from another table. What am I forgetting to set? Thanks!!
0
isladogs
by: isladogs | last post by:
The next Access Europe meeting will be on Wednesday 6 Mar 2024 starting at 18:00 UK time (6PM UTC) and finishing at about 19:15 (7.15PM). In this month's session, we are pleased to welcome back...
0
by: Vimpel783 | last post by:
Hello! Guys, I found this code on the Internet, but I need to modify it a little. It works well, the problem is this: Data is sent from only one cell, in this case B5, but it is necessary that data...
0
by: jfyes | last post by:
As a hardware engineer, after seeing that CEIWEI recently released a new tool for Modbus RTU Over TCP/UDP filtering and monitoring, I actively went to its official website to take a look. It turned...
1
by: PapaRatzi | last post by:
Hello, I am teaching myself MS Access forms design and Visual Basic. I've created a table to capture a list of Top 30 singles and forms to capture new entries. The final step is a form (unbound)...
1
by: CloudSolutions | last post by:
Introduction: For many beginners and individual users, requiring a credit card and email registration may pose a barrier when starting to use cloud servers. However, some cloud server providers now...
1
by: Defcon1945 | last post by:
I'm trying to learn Python using Pycharm but import shutil doesn't work
0
by: af34tf | last post by:
Hi Guys, I have a domain whose name is BytesLimited.com, and I want to sell it. Does anyone know about platforms that allow me to list my domain in auction for free. Thank you
0
by: Faith0G | last post by:
I am starting a new it consulting business and it's been a while since I setup a new website. Is wordpress still the best web based software for hosting a 5 page website? The webpages will be...
0
isladogs
by: isladogs | last post by:
The next Access Europe User Group meeting will be on Wednesday 3 Apr 2024 starting at 18:00 UK time (6PM UTC+1) and finishing by 19:30 (7.30PM). In this session, we are pleased to welcome former...

By using Bytes.com and it's services, you agree to our Privacy Policy and Terms of Use.

To disable or enable advertisements and analytics tracking please visit the manage ads & tracking page.